There is a booklet that allows you to convert knitting into
crochet and crochet into knitting at this site:
http://www.knitting-crochet.com/exchange/index.html
Hope this helps and good luck.

I sew my knitted seams and they don't show at all. I match up the knots that are formed by turning to go back to do the next row and sew them together. I use the overhand method of sewing and it works great. You can scarcely see the seam.

If you hold the wool correctly when crocheting you should have the right tension. I had the advantage of knitting the Continental way, holding the yarn in my left hand just like you do in crochet. Try holding the yarn this way.

Lay the yarn across your palm. Wrap it around your little finger, then up the next 2 fingers and between the pointer finger and the long finger and over the pointer finger. You have more control over the tension that way.