Of course. If you are not seen as a tourist, at some point they will stop you. Happens every day. You cannot stay long term on a tourist visa even with border hops.
I got heavily questioned on my first entry because I had previously been on a retirement visa. It is going to get even tighter shortly as they try to stem the stream of people trying to get round the rules.
Depends on the Immigration officer. Sometimes they will deny you on your 2nd one. It is variable. The minute they realise you are not a tourist they will either warn you or deny you. If staying long term, you need a proper visa.