quick answers
yes, walbro, tomei, no, no
yes - the pump is a worthwhile upgrade as they are getting old
walbro or tomei or any other number of brands are good
no power upgrade by changing the pump, although you might get some top end power back if it is starting to choke (but you would be able to feel that in teh car)
only do injectors if the duty cycle is almost or is at 100% - which it wont