In the past, Doctor was sort of Mandatory.
It's still good, well, good enough I get it with nearly every char, but you can do without it.
It saves you money, but later on, the game throws so much money at you you have to melt it down.

Crossbows are relatively difficult nowadays, they've come a bit short on the feat selection.
Chemistry certainly helps; You could even combine it with a chemical pistol.
How useful a feat is depends on how often you intend to use it.
I'd say it's serviceable in case a heavy melee comes close.
I can't help but notice you're frail and not intending to skill into defense, either.
You might get some survivability problems later on.