How friendly are people in this game?

It's a mixed bag, but most are reasonably friendly or at least not outright hostile.

Is it actually common to receive help from other players like that?

Depends on the request, but I'd say it's reasonably common.

I know I’ve seen some players doing things like stowing away and robbing players, is that something that I need to worry about?

Yes. Just take reasonable precautions and you should be OK. There will always be the potential to be ganked and/or robbed by other players. Just keep your wits about you and keep an eye out for players doing unusual things like following you in stations, loitering near ASOP terminals, hanging out near landing pads, etc. Also be cautious of players offering exorbitant payouts for medical beacons or using medical beacons excessively. It's a sign they may be trying to lure others into a trap. I generally recommend not equipping your character with something you don't really need for whatever mission/activity you are trying to do. Using mostly looted gear will at least mitigate any loss should you be robbed or just die as a result of a game bug and your body becomes unrecoverable, which in my experience is the more common occurrence.

I know this game has had a very long development cycle, how often are major updates/wipes?

There's usually major new build in the LIVE channel once a quarter, but it's not always on time. Also, they will sometimes extend a particular patch cycle if the changes in the build under development/testing is particularly complex and/or problematic such as was the case with the 3.18 build. FYI: Wipes aren't always full. The most recent LIVE build they wiped only currency (aUEC) and, of course, the non-permanent inventory items (medpens, ammo, sustenance items, etc.). Everything else including personal weapons, armor, ships, and components were carried over via Long Term Persistence (LTP).

There's a 3.23.2 build coming soon-ish (hopefully) with some fairly significant updates, so I wouldn't be surprised if they do a partial wipe then again. But usually with .x patches they don't do full wipes. They just reset characters and your home location. Your inventory will retained via LTP as will be your money.

There will almost certainly be a wipe with 4.0 planned for later this year. The extent of that wipe isn't known yet. CIG will usually announce before they release the build to LIVE, but it's going to be a big patch with lots of changes, so I wouldn't be surprised if they do a full wipe then.