It is best to freeze cakes plain without icing. You can freeze them, then wrap in plastic wrap, and then in aluminum foil to keep the air and moisture out. Then defrost wrapped at room temperature. You can make an icing and freeze separately in a plastic container or glass jar with a tight fitting lid. Then defrost and frost your cake with it.

I think with biscuits, you mean what we call cookies. The zipper type freezer bags work well for them and thaw them wrapped at room temperature. If you want individual servings, then place in small bags, and then place all them in a larger bag, plastic food storage container, metal tin with a lid, etc. You can also freeze them in the same sort of containers instead of the zipper type bags.
The only concern with cakes and biscuits would be things like cheese cake or items that contain cream or dairy type fillings. They must be thawed and stored in the fridge.

This link has charts that are good information:
Freezing Recommendations for Commonly Prepared Foods

Sorry, but due to the format, I am unable to copy and paste the charts here for you.

With any freezer storage, the important things are to keep them airtight and moisture proof.