@Petr Anisimov
I hope I can answer a few of your questions.
Generally, you'll want to invest close to home. There are plenty of times where people invest in another area, but the area you are going to be most familiar with, and therefore most likely to have success, is where you live. Trying to invest elsewhere, unless it is really reliable turnkey, is going to provide you with a lot of hurdles. You won't be able to easily view the properties, and could have a lot of difficultly finding people to trust.
If you have cash reserves, and the down payment available, consider the BRRRR strategy. It will allow you to build in some equity, and could accelerate your progress, if you are willing to take on the extra work.
As far as how to figure out the cost of a property, it really depends on the strategy for a property. The Book on Flipping Houses and The Book on Estimating Rehab Costs are good places to start for a flip or for a BRRRR. The Advanced Guide to Real Estate Investing by Ken McElroy is great for multifamily. As far as I know, his book, The ABC's of Real Estate Investing is also good, but I haven't read it.
Mark Ferguson over at Invest Four More has some great articles about rental properties that you could look into.
As far as figuring out your costs of having a property, they are fairly consistent. You have the monthly costs, like insurance, property taxes, and the like. You have property management costs, if you are paying for it. You have vacancy rates. And you have Cap Ex, which is things like roofs, siding, painting.
Repairs are going to be based on the condition of the property in comparison to similar properties renting in your area. You want the condition of your rentals to be at least as good as similar ones, depending on your targeted demographic. You can use estimate guides like the books mentioned above, things like Home Advisor, and calling local companies. It's a little odd, but the larger the scope of work, the easier it is to get accurate ballpark estimates from companies. "Replacing some siding" is very subjective, and can't really be bid over the phone, where "Replacing all the siding and wrap on the entire house with xxx sqft of surface area" is complete enough for a ballpark.
When it comes to repairs, it can be very difficult to bid things without seeing them, so keep that in mind when calling contractors. I do specialty contracting with painting(general license, but I only do painting), and I won't provide a ballpark estimates over the phone, because there are way, way too many variables that the homeowners can't adequately convey.
Generally, you'll want to break everything down into a monthly cost/percentage, since your rates are going to be monthly. Property management is commonly between 6%-10%, depending on the location, manager, and the amount of properties you have.
Cap Ex I believe is usually around 5%-10%, but that's also dependent on the age of the property. If you buy a property that has 5 years left on it's roof, you'll experience that cost much sooner than a property with a brand new 30 year roof, so the monthly cost for the amount of time you've held it when that expense is realized will be different. One of the reasons BRRRR can be great is you generally already replace big ticket items like that at the start.
Vacancy is heavily dependent on management and your area, but 5%-10% is common. Renting student housing will likely have higher vacancy and higher turnover costs than renting 3/2 singe family homes to families.
You can find the cost of property taxes from the county tax assessors website. For other market information, a local Realtor/agent will be a good source of info. Just try and find one that understands investing. The majority of real estate agents don't know how to work with investors, and don't understand it.
For insurance, give a local insurance broker a call.
With real estate, in my opinion, business plans aren't really that important. Everything is deal specific, and a business plan talking about intentions to acquire properties can be useful for goal setting, but not really for actually accomplishing specific deals. You'll have to make sure that all of your costs are included when evaluating a property, so in a sense, your analysis is going to be your per property business plan.
Exit strategy is up to you. Only you know what you want to get out of all of it. Hold the houses forever until they are free and clear and live off a decent amount of rental income. If you want to take a more aggressive approach, you can keep leveraging new properties, and using your previous properties as collateral for new loans. You could also do a 1031 exchange at some point. These are all dependent on what your specific goals are.
