@Daniel Fang - You're asking a lot of the right questions, and more importantly, you're asking them BEFORE you've decided to fall in love with this property.
In response to your specific questions:
- Find a local bank or credit union and go talk to one of their commercial loan officers. "Local" branches of Wells Fargo and Bank of America do not count. Find the "First National Bank of Your City".
- You should absolutely put a property like this in an LLC (my opinion, others may differ)
- You should talk to your CPA about tax write offs with this property. You can do a cost segregation study and accelerate the depreciation, but if you're not a "Real Estate Professional" as specifically defined by the IRS then it may not result in the deductions you're looking for.
- The benefit of house-hacking is to have access to lower rates and lower down payments of certain residential loan products. You won't be eligible for these at 5+ units.
The others who have responded all have good points. If it is at auction then it is distressed in some way. The bank is not likely to sell it under market value if they don't have to, so if it is a steep discount there is likely something else going on (extensive repairs, etc). This is not necessarily a problem, you just need to have a plan for that. The market for everything is hot right now, so even if it looks like a good deal, it's probably still over priced.
At the size and price point you're looking at, and if you are planning on putting 50% down you are in a financial position where you don't need a partner. You can take this down by yourself. If you really want to have the comfort of a partner with more experience than you in this deal, then that's ok. Just realize that splitting your equity is the most expensive way to find an acquire that expertise. If this were a multi million dollar complex and had hundreds of units, then the bank would probably require someone on your team to have experience operating this type of asset. A 6-plex is really just a 4-plex and a half with different lending rules and maybe a few different code requirements. Definitely something you can learn to handle.
Good luck!