I want to sell it and use the money to buy a primary residence.I am wondering what the tax implications will be, such as capital gains, paying taxes on items that I have written off/deferred, etc. 

Some loans may have seasoning requirements for the down payment money like you see on conventional loans for primary residences where they need to know where that money was the past couple months.

If property management is not chosen wisely you can loose a lot of money very fast.

There are a handful of ways where arbitrage ends with you running out of money. 

Be willing to spend more money or more time, but I've learned I should have spent more money and moved more quickly.

Be willing to spend more money or more time, but I've learned I should have spent more money and moved more quickly.

Infiltration (air leaks) will lose more heat than bad insulation.

He is also using a HELOC to pay for the turnover costs of losing his long term tenant and making it rent ready.  

My rehab is crawling along but I'm doing it at a pace I can afford without outside money and I'm learning along the way (that I probably want to have more momentum on my next similar deal).

When youre in housing court you should also ask for a money judgement in conjunction with possession to the property.