I always use the LAN game trick to create a 4-person custom party, and what I do is create each character and their love interest one at a time and carefully write down in a text file all the details of their creation in one game, so that when it's actually time to create my party, I can just fill in the pieces quickly instead of spending many minutes in character creation while I have extra copies of the game running.
Something similar could be done if you're just making one character at a time. Create a character to your satisfaction, put the details down in a text file or on paper, then before confirming the character, go back and change everything. That way you can quickly just match the new character with your idea by reading your notes.
I remember back before patch 4 (where they introduced the druids) someone from Larian said that update would be the last one where our old saved games wouldn't be playable after the patch.
Citation needed. I'm positive they never said that. I believe what they DID say was that you could keep playing the old save on the older branch, and that their new patching process should require smaller-sized updates. Of course that there will continue to be updates which break save compatibility - there is so much missing in the game, loads of classes, races, features, and spells.
The full release will also break compatibility with the last Early Access patch.
I can't imagine that they won't include some mechanism to allow characters to be created at higher levels, to facilitate forming parties in multiplayer. It could be a thing where you still create a level 1 character, but as soon as you join a group with a higher level character everyone is brought up to that level. That mechanic is already in the game. It happens whenever you leave a character at camp for a while. Next time they join your party you have to level them till they match you, which could be 1 to 3 levels. The same mechanic could be used for player characters in multiplayer. But they probably have other things that are more pressing to work on right now.
Why can't you imagine that? The early game is balanced for low level characters. It would be quite difficult to try and scale the entire game (encounter size/type, enemy skills/spells, NPC stuff) to match variable levels, given the immense complexity of D&D.