Generally the best login service is Sitelok by Vibralogix. There are a set of stacks that help with RW integration by Joe Workman, but they’re not required.
For e-commerce, there are not a ton of options.
Rapidcart Pro4 is the most common plugin. It has a one-time cost. There have been some support challenges with some people on the forum but it’s probably the most widely used. (Personally, I’ve found it reliable but I’ve also only ever needed it for relatively simple things and have kept it as stock as possible, without modifying things too much).
Cartloom is well reviewed but it has ongoing monthly costs. It’s the choice for many of the developers in Rapidweaver.
ECWID is another well-reviewed 3rd party option that integrates well. It has a free, but limited, plan if you only have a handful of items to sell. Otherwise, you’d pay a monthly fee.
That’s not an exhaustive list, but 3 of the more common options. Might depend on the specific needs of your store.