Before you jump into this, do some planning and figure out what your trying to keep in the system. I've posted this many times before, but it's the best advice I can give to someone new.
DaveK's Standard Lecture #1 – Advice for people new to the hobby
The very first thing you want to do, before you spend any money on equipment or livestock, is get yourself a few good books on state of the art reef systems. Then read and study them, so you have some idea about what your are doing.
Here are two to start with -
The Conscientious Marine Aquarist by Robert Fenner
The New Marine Aquarium by Michael Paleta <---This book has an especially good section on fish suited to someone starting off in the hobby.
A note on the books. You can often find used copies at much lower prices at places like Amazon. In most cases these are going to be as good as new copies, especially when your first learning.
This is information that you can not easily obtain from the net. While it's out there, it's all over the place, and there is a massive volume of information. There is also a lot of bad information out there.
Once you get that done, plan or rethink your system. What do you want to keep? Do you have the necessary equipment? Do you have the knowledge to keep the livestock you want? Do you have the time to dedicate to keeping a system and it's livestock?
Many salt water fish, corals and inverts often have very specific requirements. Some are extremely difficult to keep alive, even if you do everything right. Before you get anything, research it, and be sure it will work out in your system.
Lastly, you will find that most LFS people are clueless when it comes to SW systems. Verify their advice, until they prove otherwise.
Now to your specific questions...
I would not recommend putting the tank in your office at work, unless you own the company and the building. Managements can be very fussy about things like aquariums, and decide that it's a "hazard" because it might leak or cause a fire because of "all that electrical gear".
"Best" is a relative term in aquarium projects. What I would consider "best" someone else might consider terrible. A lot of this comes down to what you want out of the system. There are advantages and disadvantages to almost every choice.
When it comes to rock and sand, you really can't go too far wrong. For sand use aragonite sand and avoiding the extremely fine "sugar sand" and the really course sands. It need not be sand with bacteria, since once the tank gets going, it will have all the bacteria you need.
For rock, you can go with any combination of live rock and dry rock. Dry rock costs less, but the tank will take longer to mature. Again, you can't go too far wrong here. I would tend to use about 90% dry rock and 10% good live rock with a lot of things living on it, but I wouldn't call any other choices wrong.
