How do you create a database for foods typically eaten

You have to look things up the first while but as soon as you start logging MFP will start building a list of your most recent and most frequent choices automatically.

You could pre-log the foods now while you have time -- maybe add them to a date a week out, then they'll be in your MFP "recent" and "frequent" categories (or "my foods" if you have to create new database entries yourself) when you start adding them in the next couple of days. Then, when you get to the point where you pre-logged them, you can delete them if you're not actually eating them that day. If there are some pre-logged foods you haven't actually used by the time you get to the point where you pre-logged, but you still want to keep them in your recent and frequent categories, just "copy to" another date a week or so out before deleting them on the original pre-logged date. (I hope that's clear.)

Since most of the foods in the database are member submitted, I find that most of the food brands that I eat, even if I think they won't be there, actually are there. I've had to enter very few of my own foods.

Yes, but do you do need to be careful, because some of the member-submitted entries are wrong, and others are incomplete (they may not include any info beyond calories, so if you track other macro- and micro-nutrients, that information will be missing for those entries).