1.How strong do I need to be to begin training aerials?
The quick answer–you don’t need any amount of upper body strength to begin training aerials–that said the stronger you are, the easier it will be for you to progress quickly.
Most aerial instructors assume that new students coming in have never tried anything like aerials in their life, and are not used to lifting/pushing/pulling their own body weight. Many will start you in a sling/ aerial hammock (a set of fabrics with a knot tied in the bottom) to get you used to the feel of fabric before making you support your own body weight.