Monty. The sun is tough on pressure treated lumber as it draws the moisture out of it rather quickly. Being that it is winter, with less sun hours you have some time. I would recommend sealing / staining it with a high quality sealant / stain as soon as the temps are high enough to do so. Follow the instructions on the can, for minimum temps, to get the best results. Congrats on having a new deck !! For maximum life, I always retreat based on how the wood looks, even if that is annually. Hot dry long summers will be a lot harder then cooler shorter summer seasons. Also take into consideration what your decks direct sun exposure is, if the sun only hits your deck directly in the mornings it is better than if it in directly on it from 11am to sunset. I don't let the snow set on mine either. Hope this helps.
Quality. Straightness, Less tore up edges, always remember to crown your lumber.
Yes. Treated lumber used to construct raised vegetable gardens and flowerbeds are increasingly popular and practical. Recent scientific tests prove there is no significant uptake of preservatives into plants.
I suggest a proper primer and topcoat of 100% acrylic premium paints has the best chance of adhering and withstanding the excessive moisture and shrinkage of pressure treated lumber. Know when to apply a paint by dripping water onto the deck surface. If the water quickly absorbs into the wood it's time to apply a wood sealer — If the water droplets bead up, your deck is protected. Be sure to test annually.
No gap at all. This wood will shrink to leave a 1/4 to 3/8 gap.
This is a wet wood/pressure treated, it shrinks as it cures. Butt it together when installed and you will get a nice 1/4 to 3/8 inch gap once it cures. Ventilation is important and the boards will open up rather quickly under the hot summer sun giving you the necessary ventilation.