yes
yes, and Bubble is pretty fast at this
You can set up the on page views and searches however you want. However, someone with tech know-how can access your records unless you set up privacy rules.
Bubble’s privacy rules could be set up to only allow Users to see their own UserContacts info (their connections and categories). Privacy rules can also be set up to allow Users to see their own information. But if you need Users to be only partially visible to other Users (like name and location only), and then if they are connected they have more visibility, unfortunately Bubble has limitations in searches embedded within privacy rules (search the forum and you’ll see discussions on this).
However, privacy rules can be set up so that User information is only viewable if the User is in current User’s list of Users – so you’d need to set up a list field in the User to hold each User’s contacts. But if you need the categorization ability, you’d still need to do the UserContact table to hold those categories.
You couldn’t accomplish your categorization issue this way. You could put a User’s list of contact Users in a list field, but that doesn’t enable you to assign the categories. You need a table like UserContacts to hold them.
But putting that aside, regarding list fields… great post on this below. The goal with databases is to keep them light, and the experts say that loading down each User record with a list of records should be avoided where possible. Comes down to scalability though – if you don’t anticipate a large database, then most ways will work fine. But if you anticipate getting very large, then taking the optimal way is important.
Alternative approach to the Bubble’s recent tutorials for list of things