Hi Gary hope you had a good new year.;

Every time you make a new layer ,what you are in effect doing is making the file larger , by flattening the layers you will reduce it. Also if you save a photo with 2 or more layers as a jpeg, when you reopen the file you will loose the other layer/s. If you want to save a photo with more the 1 layer save it as PSD. When |I edit photos In use this if I'm not finished editing and have to go leave my computer .

The easy way to alter colour with a lasso selection ( if I remember you are using CS3) is
1 make your selection
2 go image -adjustments-colour balance
3 you will see sliders just play around with them it happy
Another way
Instead of image adjustment colour balance is go image adjustment hue and saturation
in the box you will see master
click on the drop down
select the colour you want then move the sliders to suit.
If you have any problems just put a post up... Good luck .. Graham