All these things should be checked before you sign the lease.
it is a contract. Read it, understand what your options are.
If all else fails.....go to the office, express your concerns and see if they will cancel your contract.
Owners are typically allowed to enter the premises at reasonable times with or without advance notice, probably on most leases. Smoke detectors are cheap and if the owner doesn't install them, you can do that yourself. However my guess is if they are not installed to code, you ask and they will install to code.
Mismanagement....that's pretty hard to prove....according to who.....probably not a valid reason to break a lease.
Crime is everywhere.....this probably has not changed much before, during, or after you signed your lease. Be careful everywhere, not just at your apartment, but shopping, at work, while travelling.
Probably not what you want to hear, but you signed a contract. You want them to honor their part and you should also honor your part. You wouldn't want them to come to you if you were happy and say they had someone who could pay more rent, or rent faster, or a bigger deposit, or didn't care about smoke detectors and wanted to break your lease, so they could put that person in your apartment.
Move in...be happy....if you don't like it...move when your lease is up.