- The rules FAQ that one of the moderators put together states that your opponent could still use a weapon if it were reasonable that he do so, so if you grab a leg and he has a sword, he can stab you.
- The same FAQ stated that reactions may be possible if circumstances permit.
- Good question about Reach. My opinion is that if they are grappled in a way that does not permit Reactions, they don’t get the advantage of Reach, but I didn’t find a reference for it.
- Rules say the grappler can’t move away from the target without releasing the target; don’t actually address your question – maybe the FAQ does, because it has a section on grappling.
- I would strongly say no.
FAQ link: Unofficial Rules FAQ, Sorcery Cheat Sheet, and big list of links!