Some guidance needed for newbie - hire system

Not sure if this is in the right place (maybe it belongs in the SQL Server forum, but I thought it sounded a bit more general than that)

OK so I'm in the process of developing an SQL Server (Express) db with a C# winforms front end. I am a complete newbie to SQL Server, and am not that experienced in databases bar some simple hacking around in Access.

It's for an audio rental/hire company.

I have a couple of questions:

1. There is a sort of 'main' database (called "EMS_Main" at the moment which holds a load of mundane stuff like a list of staff, discount types etc etc, and also some more important stuff like a table with some basic quote details (quote number, status, dates etc). What I'm struggling with is how to store the details of those jobs. Each of these jobs has a 'specification', which in itself will need to be a separate table of data, and then some other tables too (e.g. logistics details, venue details etc).

So I end up with this scenario of having a job which is a record in EMS_Main, which needs to have multiple tables attached to it somehow. So what's the best/recommended way to do this? I was toying with the idea of creating a separate database for each job (we quote for ~1500 jobs per year, so that's a lot of databases and tables), and just changing the connection string in the code, but that sounds excessive, possibly a recipe for pain later on, and I don't even know if it's possible (I'm guessing there's an upper limit on number of databases). Is there a nice, easy way to organise this within EMS_Main (can tables be put into folders or classes or something? So I could refer to them like EMS_Main.[folder].[table].[field name]), or am I barking up the wrong tree?

2. Equipment clashes. This is where e.g. the office boys are quoting for a job that's 6 months away, then 3 months later they quote for a different job that happens on the same day as the other job. They spec some of the same gear for both jobs, so that we are short on stock that day. I need a way of flagging this up and generating a list of stuff we're short of. Is this possible on a job-by-job basis? I.e. so when they spec the gear for the second job, the frontend will be able to throw some options at them to change one or the other of the specs, or would it have to be done (as they do it at the moment in an Excel/VBA convoluted mess of a system) e.g. a month at a time by a separate process/query altogether (i.e. a guy opens up a form, hits 'go', and is presented with a grid of stock items vs dates with quantities in the cells)?

I guess I've jumped in with both feet here. Hoping I can learn to swim in time!

Apologies if the post isn't written very well, it's difficult to get this stuff down on paper (screen?) without drawing a diagram...

Thanks in advance