I do iron mine , it gets it a bit flatter and the pressure does seem to make it all stick a bit better.

If I can I iron after spraying, it does make the back smoother. The one thing I do like with 505 is that you can reposition, even if you notice a wrinkle part way through quilting. Sometimes though, because of quilting I can not change but sometimes I can. Great stuff! And I do not use pins either.

I sometimes iron it if the top or backing needs to be a little smoother. A lot of times it's not necessary. You just have to decide on each project whether it's needed. But it is definitely not required.

The tutorial about ironing might have been using washable glue, not 505.

This may sound crazy, but I do my basting standing up. I pin a bedsheet over my design wall, then put up my backing, right side down and spray the top 1/4 of the backing. I position the batting (an extra pair of hands really helps here) and smooth it down, then pull it back up to where it needs to be sprayed. I spray another 1/4 of the backing and smooth, then another 1/4 and smooth, then the last 1/4. Then I repeat with the top, but I pin the top about 1/4 down, then let it fold down and spray the fabric. I was taught not to spray the batting, because you get better adhesion by spraying the flat fabric rather than the bumpy batting. Then I lift / spray / smooth the rest of the top. I do use a pin to mark the center at the top and bottom on the backing, batting and top to try to keep everything centered. Once I have it all sprayed and smoothed, I turn it over and smooth out the backing. I do it this way because I can't get on my knees anymore, and I don't have a flat surface large enough to lay it out on.

Patsy Thompson has a You Tube video that demonstrates how to spay baste on your design wall like Mckwilter just mentioned above.

http://www.youtube.com/watch?v=2UoUzK19Vww