I would invest in a cheap mig even from HF. Practice on light tacks . You could do this with a stick and some small rod with a copper backer just tacking a few spots and letting it cool then coming back to it . Even at the age of 52 i am learning a lot myself also found out you never quit learning more .

Body work do a search on line lots of great info sites showing the basics to some light repairs . As Dave said body plastic is best when done in a repair real thin .