Well....so many things to comment on, but I'll just stick to some of the basics.
Everybody who makes safes has them tested differently. If a safe is 12 ga. steel, and has 2 layers of 5/8" gypsum board, it's going to keep the fire out the same as any other safe of the same construction. One safe may have a 45 min. rating, and one may have a 60, but don't think that the 60 minute safe is better just because it has a sticker that says so.
Liberty, Pro-Steel (Browning), and many of the other safe companies are importing their lower lines ($1,000 and less) from China. Why pay for the name when you can buy the same safes, from the same factories, with a different name for less money?
Gun safes by their very design must be large enough to hold firearms, yet light enough to go into a house. As such, the steel used in them is usually pretty thin. The imports typically use thicker steel than the American made counterparts. The thicker the steel, the more security. The more fireboard, the more fire resistant. Get as much of the two as you can afford.
If you want an American made safe in that price range, Granite Security makes an ok safe, as does AMSEC. Fort Knox which somebody mentioned makes good safes, but are much more expensive.
If you don't mind having an imported safe I have some Diamond Back's listed on my website. I choose the Diamond backs because they use 1/8" (10 ga) steel bodies, and 1/4" plate in the doors. They do not add any fluff (additional relockers, hardplate, fancy paint), but upgrade the essentials (steel thickness, bolts on all 4 sides of door, gear driven boltwork). They have 6 models, most of which can be had for under $1,000.
As far as a warranty......this is why you should buy safes from a safe company, and not a gun shop or a big box store. When somebody I sell a safe to has a problem, I go out and fix it. I don't tell them that I don't have a clue and give them a 800 number to call, or instruct them to bring it back to the store for an exchange. Guys like me are also able to inspect the safe prior to delivery to make sure everything is in working order.
As far as the fire, theft, and flood replacement warranties.....that's what your homeowner's or renter's policy is for.