Hi, stitching half stitch on 14ct wouldn't change the size, just the length of time to complete the stitching. DMC actually had some information on this style of stitching that I think will help you out: http://www.dmc.com/majic/pageServer/0801010321/en_US/Half-Cross-Stitch.html
It does mention using Pearl Cotton but you could use regular floss. I think 3-4 strands should give you nice coverage. I would suggest doing a little sampler of different strands numbers to see which one works best for you.
I hope this helps. Also, I hope to see some pics of the project.

I have stitched on Linen before and really enjoyed it. Once the first handful of stitches are in, it is a breeze. Just relax and enjoy it. Awesome design and fabric, btw.

Hey I saw this on the SanMan Board! Again, I look the colors and the embellishments you used. Look forward to seeing what you finish it into.

That is fantastic! I just watched that episode like two days ago. Very awesome and very creepy. I look forward to seeing the whole costume put together.

Aren't you the cutest in your pink dress! It turned out fabulous!

A-freaking-dorable!

She is adorable! Her costume is superb!

Those are fantastic! Great stitching and great finish!

He is adorable!

Amazing painting! My favorite is the very first one but then again, I am in love with ladybugs.