I like the tarantula shot - aperture rules all!..... like Ric said, a tidge more focus and you are
well on the way.... I wouldn't worry too much with RGB for a bit - I've had mine for a year, have only just started mucking around with the filters....
Tuc47 - looks a bit overstretched - almost a 1-bit image..... Good start though.....
Nebulosity isn't free, but knocks spots off of envisage!