Nick O'Dell has it right, to expnd a bit on the last question:
'What implications do blocking port 8333 have on my bitcoin daemon from getting transactions? Does it get less transactions or get transactions slower?'
It has no impact, there are only ever 8 outgoing connections even if you disable this port or set listen=0. If you set maxconnections= significantly lower than 8, then you could (I suppose) start to have problems if your addnode= or connect= were connecteing you to a few slow/intermittent peers.