Can you add a recipe to upgrade boilers to heat exchangers?

Litearly just did. It is in the latest version for 0.18.0

Oh. I didn't see that. Anyway, I have three other suggestions.
1. Can you replace the pistol in your recipe for the combat shotgun with a shotgun?
2. Can you add a recipe to upgrade an explosive rocket to an atomic bomb?
3. Can you add recipes to upgrade armor?

Point 1: I thought I had it that way, but it seems to not be the case
Point 2: Don't think I will do.
Point 3: Has been implemented for just under a year.

The reason I probably won't do 2 is that I want to keep the resources needed the same. In the case of the explosive -> nuclear rocket you would need 8 more explosives(or just 5 explosive rockets) but that would leave you with normal rockets(used in the crafting of the explosive rocket) that I would have to 'take apart and modify its ingredients' or return to the player as a crafting result(wich I think you can agree with me is kinda strange, make one nuke from 5 explosive rockets and get 1 nuke and 5 normal rockets).
Besides that (and this is a somewhat weak reason) IRL nukes aren't so much rockets(missles) as they are bombs or ballistic rockets(that go though space) so the technology involved is quite different. I don't want to be around when nukes can be fired from a hand-held rocket launcher

Does 3 include the armor items added by Bob's warfare?

I just checked, and there isn't an upgrade recipe for the combat shotgun at all. Also, I have more suggestions for upgrades:
Filter inserter->stack filter inserter
Small electric pole->medium electric pole
Medium electric pole->substation
Wooden chest->iron chest
Iron chest->steel chest

I have just made a recipe for shotgun to combat shotgun and for Filter to stack filter. I will not do so for others as they are to different from each other in my eyes.

Some suggestions for if Bob's Mods are active:
Remove:
Boiler->heat exchanger
Steam engine->steam turbine
Add:
Burner assembling machine->assembling machine 1
Electric metal mixing furnace->electric multi-purpose furnace