A 401K loan is never deductible no matter what it is for. A home loan is only deductible as a mortgage if it is perfected against the property (means it is registered as a lien with the county so that the lender can foreclose if you stop making payments.) You'r paying the interest to yourself anyway.
Improvements are not deductible on a personal home. They increase the value of the home and may lower your taxable gain when you sell but they aren't deductible.
You may be able to deduct mortgage interest you pay, if you pay part of an actual mortgage (not the 401K loan). You have to be considered to have an equitable ownership interest in the house. That is, a judge looking at your living and financial arrangements would have to agree that you are an owner in fact even if you aren't an owner on paper. The finding depends on the circumstances of each individual case.
You can't deduct property taxes if you aren't on the title. The equitable ownership rule only applies to mortgage interest.
Make sure you took a loan from the 401k and it wasn't a Distribution. A loan is not taxable and you don't get a 1099R for a loan. If you do get a 1099R for it then it wasn't a loan.
"The equitable ownership rule only applies to mortgage interest."
Paragraph (3) of this reference cites U.S. Tax Court decisions stating that an equitable owner CAN deduct property taxes: