Tretinoin (retin a) has made my skin extremely dry, is this normal?

Yes. Tretinoin (retin a) typically causes dryness of the skin. Applying a good facial moisturizer/sunblock twice a day should help out quite a bit.
Yes. Tretinoin will always make the skin dry and "flakey" as it increases cellular turn over which cause the older skin cells to slough. When using tretinoin creams i always have my patients begin very slowly, maybe 2 or 3 applications per week for the first week or 2 with progressive increase in frequency. The "problem" is usually "self-limited" which means the dryness eventually stops.