I am having the same problems with WiFi every once in a while. Seems to just go away after several retries, or after restaring the phone. I have no idea what's causing this. Luckily, it doesn't happen often, and is not a huge issue...
As for the SIM card issue, it seems like a mechanical problem to me. Did you cut the card yourself (it can be tricky), or was it an original micro-SIM? It may be a loose fit of the card to the tray, if dimensions are off. Otherwise, it may be a problem with contacts, or the tray itself could be loose in the socket. In these cases, professional service (warranty?) is probably your best bet, unless you are comfortable fiddling with it yourself. I can tell you that getting to the guts of the SIM card socket of the OG is not exactly a trivial task...
Optimus G F180S, tweaked E975 Stock 4.1.2
MeMO Pad HD 7 ME173X, rooted stock 4.2.2
To whom it may concern: STOP nagging about pressing the freakin' Thanks button!!! It is rude, stupid, and annoys the hell out of people. I am not an idiot who needs a huge in-my-face reminder to press it, and I will press it when I feel thankful, not because you asked for it!