Need to know what the recommended " map " size is. I'm planning to order a custom mat or two so they arrive in time for release day.  

 Unfortunately, that's something we'd all like to know. According to what we heard at gencon, there is no set size, but whatever table you play on, if your fighter goes off the table, it is immediately destroyed. From that perspective, a larger mat may be better to give you more maneuvering room, but we can't say more than that.

i was hoping to know too to build a space gaming board, i suppose short term a sheet of black cloth over the kitchen table might work.

 Here is an easy method I used years ago for a space combat game. 

Go to a craft store that sells fabric. If you have a Hobby Lobby nearby that's a great choice, since most weeks they put a 40% off one item coupon on their website. I used a heavy vinyl so it wouldn't wrinkle and also gave a bit of friction to keep things from getting slid around too easily. You can probably get two 6'x3' pieces for around $10-15 that could be combined to make a 6x6 play surface, should be more than enough for any size battles.

While there get some acrylic paints, usually about $1 for a 4oz bottle. Get white, blue, and red at least. 

You will also need a toothbrush, an old one is fine otherwise get one at a dollar store. You will probably want some cheap plastic gloves (like dishwashing gloves) as well. 

All you need to do is dip the toothbrush into the white paint, then blot it a bit so it's not too heavy or runny on the brush. Hold the brush a few feet above the fabric and draw your thumb across the brush, flicking small sprays of white paint onto the surface. You can get different results by holding the brush lower or higher, using more or less paint, and dragging your thumb fast or slow, so experiment.

Mix a little bit of blue in with some white to get different colors. Red will work well as it comes and with some white blend. Most of the starfield should be white and blue so mix in other colors sparingly to keep it more realistic looking. Bigger dots of paint will look like brighter stars, while small dots look like faded or distant stars. 

That should get a great result but you can also experiment with a sponge and some different color paints to get some nebula looks, just keep the paint very light.

 I also remember that when Starship Battles came out, lots of people were using this 'space' printed fabric that Walmart was selling at the time. Maybe they still are? You could buy it by the yard for pretty cheap, as I recall…

 I am a big fan of the 2x3 3x5 or 4x6 or 4x4 size, depending on game size. But since there's no set limit….