Can I transfer to a four year university after one semester of community college?

Generally speaking, yes.

I would contact the four year university directly though and ask them what their requirements are. Bear in mind though that depending on the four year institution and the program you are interested in, they may not accept the credit transfer (meaning you would start from scratch), allow you to just place out of basic courses (meaning you would still have to fulfill the complete credit count requirement), or accept some of them but not others. If you went to a community college with a direct transfer agreement with the particular four year institution your credits will be more likely to transfer, but sometimes they only completely accept them if you have completed your transfer degree.

This probably would not affect admission likelihood per se, but it would just mean that you have to retake credits.

It is possible to transfer but the university may not accept you.

yes

i think it depends on where you wanna go. I would just apply and see if you get in.