Hello SimPenguin,
For your first problem:To help you when placing a lot, you can try to hold the
Alt key. It works like in Buy Mode when you place objects, you can rotate freely the object, or the lot in this case. Yet, it's not a Snap To Grid method.
In fact, I think that without the Alt key, there is a kind of snap to grid by default. But it snaps to the default grid in CAW, at 0° rotation (you'll understand what I mean when you'll try CAW by yourself
). The problem is that the roads, sidewalks and lots in a world are sometimes placed at a different angle. This means that when you try to place a new lot in game, the lot will snap to 0°, 45° and 90° angles, when the others 'things' around are placed at odd random angles.
Then, you must
always have a buffer zone between 2 lots. This zone is 1 tile wide. There is absolutely no way to place 2 lots closer to one another, neither in game, nor in CAW. It's not possible to have real looking very dense city environment in Sims world. Besides this, denser worlds have a heavy impact on performance. You might want to check that your computer is able to handle such a world.
Second problem:The path the Sims follow when they travel from 1 point to another is handled by something called the routing. Basically, in CAW, it looks like a network made of triangles and matching the ground.
When you edit the lots in game, this routing map needs to be regenerated to take your modifications into account. To do this, you must reload your save. So, after you've deleted a lot or an object, save => exit to main menu => reload the save you've just left.
You should then be able to place a new lot.
Hope it will help you solve your problems.