Great choices, all. These are some of the higher quality kits, so they may run you up a bit. To be fair, though, the fit on Master Grade (MG) - indeed, on all Gundam kits- is so good, you don't need to glue them unless you want to. As far as I know, these kits all have the "inner frame" over which the exterior panels attach.
the Shin Musha RX-78 is a what-if creation by the chief Gundam designer who created the designs of all the Gundams in all the series. He went back and added redesigns and what ifs just for fun.
F91 is the titular " hero suit" of its series.
Ditto for the G Gundam, though the series it is the star of is in a world of Battle-Royal style tournaments between the Gundams of various countries (in case you could not guess, the G Gundam is Japan's representative suit).
Gundam AGE is a (relatively) new series, and I don't know anything about it.
keep in mind, each of these suits are from different series, and all but two (RX-79 and F91) are from different 'universes', i.e. Timelines, each independent of the others.
Klik