First of all, welcome to the hobby!
To answer your questions:
A typical boil length is 60 minutes.. Basically the boil time can be adjusted if you want higher IBU or higher OG.
You can stuff more hops in a 90 minute boil than a 60 minute making your IBU higher.. if that's what you're into.
If you want a higher gravity beer you can boil longer.
Here is a pro tip: An easy way to estimate/calculate starting gravity (OG) is to measure the gravity and volume pre boil. Say your pre boil OG is 1.050 and you have 7 gallons starting volume. Multiply the gravity points by the total volume to find your total gravity points. In this case it would be 50*7. This gives you 350 total gravity points. To find the OG after boil just divide your total gravity points by your ending volume. If you end with 5.5 gallons then your starting OG will be 1.063.
This is useful if you want to make a beer that is a certain ABV%.. If you know that your boil off rate (how much vapor you lose per hour in your kettle while it is boiling) is 1 gallon per hour (a typical boil off rate) then you can find out how much you need to start with in order to get the OG that you are shooting for.
Boiling longer can also correct mash efficiency issues but you will end up with less than 5.5 gallons. I had a beer that I made recently where I was shooting for 1.080 OG and I ended up with 1.070 pre boil OG. If you do the math, ending with 5.5 gallons only gets me to 1.076. What I did was boil until I had just over 5 gallons of wort which brought me to 1.081.
To address your dry hopping question...
There is a lot of information and mixed opinions on dry hopping time, temperature, amounts, etc. There are several
XBMT's on dry hopping since it is an area of brewing that isn't 100% figured out yet.
For instance.. A lot of NEIPA brewers (including major breweries) advocate dry hopping while there is still plenty of yeast activity going on. This is against the mainstream thinking of dry hopping AFTER fermentation is almost completed. I have personally dry hopped both ways; I have dry hopped for 2 days, for 4 days, for a week, etc. For a NEIPA beer such as this one you might benefit from dry hopping on say day 3 or 4.. somewhere in that range.. in order for the yeast and hops to cause "biotransformation." The best advice I can give with dry hopping is to just experiment and make the beer to YOUR preference.. that's the beauty of this hobby. You can adjust the ingredients and processes according to your preference.
As far as the fermentation question:
Last but certainly NOT least. Maintaining fermentation temperatures might be one of the most important parts of brewing beer. I brewed beer for a while without being able to control the temperature very well.. my beer wasn't very good.
There are a few choices here:
The cheapest method would probably be to place the fermenenter in a rubbermade bin with water to maintain the ambient temperature. If the temperature gets too high you just add ice to the water. If it doesn't get warm enough then some people use aquarium heaters. This method may work but won't be the optimum method. This will be cheaper but not by a lot: aquarium heater - 30-40$, rubbermade bin 10+$ which leaves you around 50$ give or take.
The only other method I would present as a new homebrewer would be to use an old refrigerator coupled with an
inkbird controller and a
carboy heater. The inkbird controller plugs into your power outlet and has a "heating" and a "cooling" outlet next to the temperature controller. The refrigerator would then plug into the "cooling" outlet and the carboy heater would plug into the "heating" outlet. The temperature can be set to +/- 1 degree F and if it gets below the threshold it will either turn on the refrigerator until it reaches the temperature or it will turn on the heater.
Now for the math - I got my refrigerator for 10$ on craigslist.. it doesn't have to be pretty it just has to work. The inkbird was 30$ on sale (3$ off) and the carboy heater I got on sale for 9.99. This got me to 49.99 - if you add the extra 20 for the heater not being on sale it will cost around 60$. 10$ more and you can control the temperature within 1 degree F without having to blink an eye.