You probably don't want to buy another bottom bracket, since it's a French threaded one you will need and they can be hard to find. You can move the right crank outward 2-3 mm with bottom bracket spacers (aka freewheel spacers) behind the the drive side cup flange. The non-drive side cup will recede into the bracket shell a bit, but that's no biggie. Check that this won't bring the non-drive side in so far that the left crank comes uncomfortably close to hitting the chainstay. You need a bit of clearance for safety and for the crank to settle a bit onto the axle over repeated tightening. Maybe this will bring your front derailleur into range. Don't worry about your cranks being off-centre a bit, as long as there is chainstay clearance. Also don't fret about chainline as long as you are within a few mm and the whole thing works reliably and smoothly.

Spa Cycles in the UK has a variety of chain guards for those 110/74 Sugino cranks, and an amazing collection of chainrings of all qualities too. Making a triple into a low double is a standard trick "over there", and the chain guard will really look like it belongs on that Peugeot. I say go for it. BTW, that bike deserves metal fenders and nice tidy little rear rack.