Going to Home Depot or Lowes or hardware store to buy materials for your rental6.

These line items are meant to be reserves you stash away for a rainy day, so there's no harm in over-estimating them. 

Also don't price things aginst what they cost to rent, rental stores often times change upto 80% of the product cost to rent. 

The thing you want to avoid happening is the IRS deeming you that you live in multiple places and your travel then potentially becomes non-deductible(depending if you do have a business).Items such as registering for a new state ID, paying for utilities, applying for state voting, etc help establish your new tax home.

I prefer to put every line item down with almost an exact cost so I can get hard numbers and have the % returns based off of those numbers, not the other way around.If I walk into a place with brand new roof, furnace, windows, kitchens, bathrooms, with quality construction, plumbing, etc...

A 8.5'x14' trailer can store a lot of tools when rigged up with shelves.

Do they have a cost for construction and itemized list of equipment? 

Here is the process I recommend for learning how to estimate rehab costs:#1 Read the Book on Estimating Rehab CostsJScott's 'The Book on Estimating Rehab Costs' is a great resource for new rehabbers to learn how to Estimate Repair Costs on 25 common rehab repairs.https://www.biggerpockets.com/store/the-complete-g...#2 Explore Lowes and Home Depot to Learn About Material PricingTake a tour through Lowes and Home Depot (or their websites) and look at finishes materials and fixtures that you will consider using in your rehab projects.

I'm going to go to the local UPS store to get a mailbox this week and will begin sending letters.

Obviously, the best approach would be to map out all the interior CapEx items and their expected useful life.One more thing to keep in mind: exterior CapEx might be "covered" by your HOA fees, but if the HOA isn't well managed or there's a big unexpected expense, you might get his with a special assessment.