Throwing my self on the mercy of the community

I don't see anything in your description that couldn't be handled by drupal. And the very fact you mention You don't have a lot of spare time would indicate that you're better off using a CMS than coding from scratch. That said, there is a learning curve for drupal and that has to be factored into the mix.

More often than not when I encounter coders struggling with learning drupal, it's precisely because they are coders and trying to work with drupal from that mindset rather than adapting to the 'drupal way'.

And you don't mention much about your lending use case, but from what you've written here, I would think MERCI would be way way overkill for just a simple lending library. Maybe give agreservations a try.

Unique ID's are built-in to content types so that shouldn't be an issue. And when it comes to linking items, I generally use entityreference, entityreference_prepopulate, and auto_nodetitle. However, if you're not using content types (but I don't see any reason not to based on your description), you would need entity_label which I haven't tried yet. Taxonomy is also a way to link different things across content types. For ratings there's fivestar or rate. And of course, the great views module for any and all listings and custom searches (done with views exposed filters).

Honestly, I don't see anything here that couldn't be done pretty easily by someone who knows drupal, so it's likely the learning curve that's giving your problems, rather than any actual limitations of drupal itself.

That's doesn't really help much... it's pretty much up to you whether or not it's worth the learning curve. However, I've recently come from a project for which I had to use c# and omg I hope I'll never have to that again. Something not much more complex than what you describe here took like 6 months to code completely from scratch (including all the jquery and manual ajax and whatnot) and would likely have taken at most a month with drupal (if not less).

And I noticed you only just joined drupal.org-- so you've obviously not being seeking help here. Often a couple of targetted posts can get some good responses and get you past a bump or two in the road while climbing the learning curve.

There are a few building blocks in Drupal you need to learn. The first is the Fields (formely known as CCK). The other is Views.

The Fields UI lets you create content types, which for all intents and purposes are your database tables. They all produce nodes, and each node as an unique id.

Download Views and enable the Views UI (it will be part of the Drupal 8 distro), which lets you create views, which for all intents and purposes are your database reports. You can choose if you want to produce these as pages, blocks and a few others.

Add the modules WorldFallz mentioned (but add the http://drupal.org/project/references_dialog module as well, a super short tutorial) and you have what you need for your project.

For a simple walk through on how to use these different parts one good place is to start with some video tutorials. Wunderkraut (formely NodeOne) has some tutorials on their site, for general Drupal learning: http://nodeone.se/sv/node/36, for references this one: http://nodeone.se/sv/node/30. References can be thought of as Foreign Keys.

The references dialog lets you use views to look up other content, and in views you can use filters, thus enabling you to use text and dates. Oh, and you need the date module and perhaps the calendar module (for js calendar popups to date fields).

The entityreference_prepopulate module lets you send in data to a new node creation page, for example an id for another content. So say you are in a "TV Show page" there would be a link for creating an "episode" which would go to a node creation page where the show would be filled in already.

The autonodetitle module hides the title field and lets you create them based on placeholders or code. So the episode page could have a Name field and the title would be generated like thus "TV Show S01 - E01 Episode title" and fetching the data from the relevant source fields.

You might also like to look at conditional fields and computed fields, the first hides or shows fields in the creation pages based on values in other fields. The second computes values for you, based on PHP code. Search and you shall find pages describing them and to learn how they can do a lot of stuff.

Using Drupal for your project certainly seems feasible, in fact this is exactly the kind of stuff that is fast to do in Drupal. I called content types tables, views for reports, and references for foreign keys. If you want to take it further you can look into Rules which might be akin to triggers.

I also suggest that you search for modules using filtering by popularity, as that will give you an idea of how likely it is that the module will "survive" to Drupal 8 and into the future, as almost every major release demands some kind of maintenance of existing modules for them to work.

Best of luck, an do look into the tutorial videos available.