You can watch a large chunk of UC with dubs. ZZ isn't dubbed, and a few of the newest ones aren't dubbed yet, but otherwise it's probably one of the more accessible anime to get into. If you've only seen highlights I would say it's a good time to just start episode 1 of 0079 and roll it. It's not like every episode is amazing, but it's fun and cool to see where the story begins.

When I say Gundam I mean UC. Some of the other shows are entertaining, but they don't feel like real Gundam to me. UC has hard sci-fi elements, political, space and mech battles. It's a mix that hits pretty hard for me. Most of the non-UC shows are either goofy, or not 'real robots', or set mostly on earth.

Yes

As a Gundam fan in the west, you really have to turn to the pirates. Part of me wishes Sunrise/Bandai would get their shit together and get it all available, but as somebody who has followed the series since the late 90s it's kind of always been this way. You can buy the Blu Rays if that's your thing, but you can also find everything in great quality from multiple sites.