welcome to the MSG PLUS! forums firstly
for problem two:
go to the plus preferences and then plugins, then make sure that stuffplug is enabled in that list (you will need to sign out after anabling it)
and
for problem 1:
switching browser wont help you be able to get a signal from wireless,
if you are connected to a router (or other wireless device) at home just make sure that in "connections" that is the enabled option, it should be if firefox is working fine, if IE (Internet explorer ) wont work then neither should FireFox, maybe you'll have to explain that part of your problem a little bit more