55 would be fine.
2.) Depends on the filtration you use, and whether or not you use Live rocks, sand, or a combination. The rocks can be dry (base, dead) or "live". Your LFS
will have some, or you can order online. Depending on what type of LR
you get, you may need to add a cocktail shrimp to get the cycle started. It will break down, generating ammonia -> nitrite -> nitrate. Another search on this site for LR
.com or liverocks.com and you'll lots of happy customers. Cycle time could be as short as a few days or as long as a few weeks. Check your nh3
, n02, and n03 levels. When nh3
and n02 are zero your cycle is done. Patience is a huge requirement in this hobby.
3.) Invest in a hydrometer. (<$20) These tell you the specific gravity of the water, and add salt until your SG
is in the range you desire. When adding water to an existing system, one of the big things is to match the new water SG
with the existing tank. Fish can tolerate a reasonable range in high or low SG
but a quick swing will stress them. Note on adding salt: It is a great idea to mix the salt in a large container with a spare pump/powerhead overnight to make sure the salt has thoroughly dissolved before adding to the tank. Adding too soon will stress your livestock.
4.) You don't have to, but it will make your life much easier. The porous nature of the rock / high surface area cultivates good bacterial growth. More rock = more surface area = potentially more bacterial = lower ammonia levels = happier healthier fish. "Live" rock has been recently taken from either the ocean, or from an existing aquarium. If you are not in a hurry, you can get base or dead rock cheaper, and cultivate the bacterial colonies yourself.
5.) You can use either
Lots of folks have strong opinions both ways. Some even go Bare bottomed with no substrate at all. Do a search for CC
(crushed coral) DSB
(deep sand bed) and BB (barebottom) to see what folks have to say about each.
No worries. I am a newbie myself - going on 3 months. You are off to a great start by doing your research ahead of time, and by caring about your livestock!
There is a 'recommended reading' section here also. Give it a look. -
Hope this helps-