On your second question, yes, certainly, you can post videos of your own compositions in the Our recordings of Members' Compositions
section, and your arrangements in the relevant "Our recordings ..." section corresponding to the original composer or era. (You can see those sections, with their subsections, listed on the main forum page here
, with the dates applying to each era).
Please check out all the relevant rules and restrictions here
before posting. In particular please note that only arrangements of music in the public domain can be posted, which usually means the original composer has been dead for over 70 years.
Please also observe the standard format for the post title, described here
, to help with sorting and searching. And you can find guidance on embedding YouTube videos here
Classical Guitar Forum.
"Experience is something you don't get until just after you need it." - Steven Wright