This is my first quil and I am not usning a bought design.
1. I will be using a 8 or 9 inch block for a twin bed, I'm think 7 across and 10 long.

Tell me where I am right or wrong
1. Squares need to be measured 1/4" larger on all sides?
2. Does this also hold true for all apliques?

Which would be esiest to do apply the appliques to the squares before attaching them to each other.

Hi and welcome to the board from Iowa. I would applique onto a square before I put it in the quilt.

Yes, you will want to applique the blocks before joining them together. There are many applique techniques. Google "applique tutorials" and then try doing a sample of the one(s) you think you'd like. I think you'll really enjoy applique. And yes, you should add at least an inch extra to the block and then square up after you have appliqued:D

A big welcome from the eastern part of Texas. I find it is easier for me to apply the applique to the blocks before I sew them together.

welcome from OK.
First you need to say how big is the applique, are you fusing or doing needle turn applique?
either way, but especially for needle turn, I would start with a block that is about 3" larger than what I want it to end up being. THat way should anything go wrong, it gives me plenty of space to square up. Also should I need to hoop it, I have plenty to put in the hoop while I work on it!

I am not sure yet but my squares shll be either 8 or 9''.
my appliques 6-7".
My plan is to furse and machine stitch the appliques

Then make your blocks either 8 1/2" or 9 1/2" If you are fusing, there is no need to add any allowance around the applique. If you want a 6" applique, then cut your applique 6"

I would still leave a little wiggle room on the background fabric to square things up. For fused applique--you cut the pieces to finished size and then use a blanket, zig-zag or satin stitch to hold them down. I've even seen a topstitch used but that is rare. Sometimes the fabric gets a little skewed during the process of sewing the applique down so that's the reason I allow for extra background fabric on any type of applique.

Smart woman!!

yep applique your blocks first before joining - I always leave 1/2" extra all round and then trim to size after as the applique can take up some of the background fabric