Welcome to Colorado Kart Racing.
***Suggest you check out e-Karting News website-excellent for tech and news; do some searches on some of the questions you ask.
***Find a mentor that has the same package as you will buy.
***Pick one kart ship and deal with them.
***Determine your budget to match your excitement in karting (how much do you want to practice and race/how many series/etc.
***You will need more than just a kart: suite, stand, tools, spare parts, how to transport kart to track, $$$$ for fees/practice/registration, electronics, etc. plan on spending $5-10,000 the first yr to get started. It all depends on how deep you want to get into it.
***Spend 3-5 hr to prep your kart for a day of racing. Do you have the time.
Just some things to consider.