Missions & Complexes

I'd save for the Tengu then do L4's. Having an altnear by in a Noctis to loot is a good idea much better than going back & swapping ships.

Then I have been doing it wrong for the last 2 years. Tried to fit some Rails on my Noctis and hull tank it, but it did not go well

Level 4 missions are worth more as running level 3's. A drake has enough tank for level 4's but lacks dps so not sure what gives the most isk/hour.

I would run missions on one account and loot/salvage the completed missions with the second account but that is personal preference. Might also have to do with me always accepting faction missions so you need to loot to get tags in any case. (KoS to Gallente now though.)

Depending on what skills your second account alt has have him jump into a second drake instead. A second drake might allow you to pick up some speed doing level 4's. And you can still hop into a noctis to salvage missions while your main starts on the next site.

*IF* you have second screen and can run second client *AND* have no other account to do missions with at the same time - invite yourself for 21 day trial and add plex.
This way you have lost nothing, and gained account that can do salvaging for you (in approx 2-3 days quite effectively).
If you have second account, then it's better to train it for tengu too, and do missions on both.
If you do missions for worthless LP exchange corp, then it's worth salvaging. (consider running missions and using that synergy corp that does salvaging for you).
If you have atleast 1500 isk/LP exchange, it's better just blitz all missions and just forget about drop.

And to answer your question - While in drake - stay with L3. When you get into Tengu with atleast 4 lvl subsystem skills and 5 lvl offencive, and at least lvl 4 missiles skills... go for L4 missions, but be carefull - some are very nasty. Read walkthrough before every mission until You'll be able to do them while sleeping.
Or just go wherever you want and blow up :)

Ok, on the positive side it seems like the consensus is to stay in the drake until I hit the tengu.

As for using the second character for missioning and salvaging, they currently have zero combat skills - freighter and industrialist with salvaging abilities.

Should I therefore train them into another races ships, and increase my variability, or just go to two tengus over time?

yes, there's no need to jump between skills or waste money. Get tengu tright ahead.

Second char as salvager is just fine as long as you can play both accounts at once - either 2 screens or both on same screen taking half a space, it's your problem. but they should'nt overlap, because that makes problems sometimes, and slows you down.

The good thing about doing all missions with 2 characters in tengu's is that you don't have to worry about distance, target size or speed of the target. all other guns require either distance or size to be effective... and most missions does not match same setup.

So... If you want to be super effective, train tengu + machariel. but it won't always work because of different distances in all missions. Having 2 tengu makes that problem go away - you can do one mission with them both or run them separately on the missions of theyr own. And to be honest - average (!!!) dps of maxed tengu is not that far from average maximum dps possible.
Some will say it's double, others will scream it's even bigger, but fact is - I mean AVERAGE.
If you'll take time needed to possition projectile weapon ship in right distance, it will loose shitloads of dps while tengu can start shooting instantly, does'nt matter what, where, and why.

Your first step should be checking corporation LP shop you're doing missions for.
If you have 1500 isk/LP conversion rate or better - forget salvaging, train alt for tengu as fast as possible.
If not - change mission corp!
in the mean time you can try salvaging as you go, but the real salvage is only in lvl 4 and up. lvl 3 is just waste of time.

I'm running missions for over 2 years now, and I know few guys who's doing missions casualy, whatever where, i know few guys living in WH and 0.0. And I used to know guy who lived in low sec (he quit).
Fact is - I had to lend money for all of them at one or another point.
Yes, you might be better with exploration earning maybe even 2b per day, but then you'll go empty for a week, and it will suck.
With missions you have very steady income. you'll know how many hours you'll need for next plex, not just hope for success.

Well i'm lost where I'm going with this, so I'll just say - 2 tengu's, blitzing 4 lvl missions is the best way to go if you want to stick with missioning. Most important thing is to find good LP conversion item that would sell fast and in big quantities with maximum profit possible.
If you know none of this and are too lazy to do research, try buying this info. I might even sell few item names and corporations to work for with myself.

if alt has no combat skills at all, my suggestion would be this -
get him into drake, and start maxing heavy missile skills.
Then, when you get into tengu, go to a mission, get agro, and then come in with drake to help.
Tho I'd be salvaging until he would be able to solo missions with tengu too...
And about third acccount - you won't be able to manage 3. 3 doing missions, not blitzing - maybe. with some delays. 2 accounts on missions and third on salvaging... you'd have to have very good multitasking skills (in real I mean) and be quick like hell.
I have only small 10-15 second breaks if i'm shooting 1m BS with both at the same time... and that happens not very often.
Besides, to be 100% concentrated on a game, and to feel that you're behind with something constantly will be bad for your moreale. I know, that happened to me.
I'm not saying don't get third account - it's up to you. I'm saying don't be 100% sure that you'll be using it to salvage. It can be too much for one to handle.