Is it textured? Perhaps just choose a brownish brown in a similar color to the color of the cedar on the house? I'd definitely choose a flat paint. You're right that painting it over once the trim is on will be difficult, but I'd worry about that when that comes around (just remember you need to use latex on hardy board, oil will degrade it). Ace sells decent quality paint, choose the $30 per gallon and up options (not the cheaper $15-$20 options they also sell). You shouldn't have to repaint it for at least 5 years, and if you go with a beige/brown color, fade wont be noticeable and you can probably get 10 years before you have to repaint, so I'd not paint the trim, having it natural will help it match the house. For the siding, make sure you PRIME it first with the hardy panel primer (yes it requires its own brand primer): http://www.jameshardie.com/homeowner/improveYourHome_resideYourHome_tipsArticles_painting.shtml additionally they recommend ACE's Royal Shield 100% Acrylic Latex House Paint as the only appropriate ACE brand paint, but perhaps their guide is outdated, as the clark and kennisington seems higher priced (and generally yes, you get what you pay for with paint), then apply at least 2 coats of the latex based paint (I'd do 3 thinner coats). Their website says you should buy an acrylic latex exterior paint suitable for masonry/cement, so make sure the paint you choose is suitable for painting concrete. Do not use oil based paints/stains, stick with latex based paints. If you choose to oil prime the cedar batts, do them before putting them on, and put a coat of latex paint between the oil paint and the hardy board. Oil paints degrades hardy panels.