i know you can buy a house, but the the only house in the imperial city is a shack, i was wondering if you could take over a house and still be able to decorate the house with your amour and weapons. i know you can't use the carboards, dressers, etc though cause the stuff will be removed, but will it remove the stuff if i put my weapons, armour, on table, fireplaces, etc.

If you are on PC, then yes, you can use console to assign any house to you, so you can sleep in beds and all the items belong to you. Container still reset, of course, except sacks.

best to use mods , but in a way you can , it has many limitations and if your counted as trespassing you cant sleep or wait , its very annoying

so , yes and no

If you use console to set yourself as the owner, then it doesn't count as trespassing.