My observations on what your planning:-
Essentials,
OOO absolutely, great mod. Get the version 1.33 omod installer version then top it up with 1.34 beta5.
MMM make sure you use the MMM for OOO versions. Use TheNiceOne's MMM Omod installer scripts to make the installation process much easier
QPT3. Make sure you use the Redimized version rather than the original.
You've already got ther basis for a much improved game with just those three mods.
Beauty
I like Race Balancing Project. You get a large package of beauty stuff along with the core function of tweaking races and birthsigns to make them more balanced. It's a great mod in iteself, but also one of the prerequisites for using Integration-The Stranded Light, see below. Get TheNiceOne's Omod installer.
Roberts Male body is pretty much your only choice here
For female body replacer I use http://www.tesnexus.com/downloads/file.php?id=24078 This is based on the Exnem eyecandy body, sdo has a huge range of clothing and armour available, plus it has the advantage of coming with all the vanilla clothing and armour adjusted to fit the new body. There is an OOO version that you'll want to use, so that the OOO armours pick up the changes as well.
Smaller mods,
Don't know anything about the Days and Months or the Realistic Physics mods. If they do what their names suggest I don't forsee any compatibility issues.
Use Fastexit 2. Elven Map Redux is nice. You'll probably also want a new Shivering Isles Map.
Mods you haven't got the hang of-
Streamline. Some people have problems getting much, if any benefit out of this. It seems to need careful tweaking. Most people would recommend Oblivion Stutter Remover over Streamline. If necessary use both.
Pluggy. You may not need this, not many mods require it. Note that you do not need Pluggy to use OBSE Plugins.
OBSE. In my opinion essential. You will need it for Fastexit 2 and Oblivion Stutter Remover anyway. Follow the installation instructions and forget about it. Get the latest version 18 beta. An increasing number of mods require version 18 even though it is not yet final.
OBGE. I would stay clear, at least initially, unless one of the mods you really want requires it. I believe that there were performance issues with the original version. The new version (there will be a thread floating around here somewhere) is still in its early days and it comes with lots of health warnings.
I think that your list is actually quite a solid starting line up (with the proviso that I don't know anything about two of the small mods you mention, and that you need to add the OUP) I see no reason why they won't work together.
Additional mods
Essential (IMO)
-Unofficial Oblivion Patch, and its SI and DLC equivalents. Get them.
-BOSS (better Oblivion Sorting Software) a great tool for automatically sorting your load order (or most of it anyway)
-WyreBash. You may just get away without this utility's Bashed Patch feature with your current list (not absolutely sure) but you will inevitably run into mod conflicts as you expand further, which can only be dealt with via the Bashed Patch. I suggest you get it early and learn to use at least the Bashed Patch.
Other mods/areas you may want to think about are-
Viewable distant objects. The Standout mod here is Really Almost Everything Viewable When Distant (RAEVWD). Can have a big performance hit, but worth it IMO. It's modular so the performance issue can be managed by only using certain components.
A magic overhaul. I use LAME. Again TheNiceOne has made an Omod installer.
Change the Cities. The big two here are Better Cities and Open Cities. Very different approaches, but both very high quality.
Change The User Interface DarN or Dark DarN are the market leaders.
More interesting wilderness, see the Unique Landscapes Series
Lit windows at night (and smoking Chimneys) Animated Window Lighting System
Quests Too many great quest mods to mention, but a few stand outs are The Ayleid Steps, Integration-The Stranded Light and Windfall.
Cobl. Don't know how to classify this mod, but it does a number of clever things, principally it takes items unique to mods in your load order, and where appropriate, distributes them to other places in game, eg to merchants or as random loot. It also has a number of useful smaller functions (denock arrow, spell delete, on the fly timescale adjustment, Salmo the Baker gets a shop, The Luggage). Lots more. In fact, this should be in the Essential bit.
Enhanced Economy by TheNiceOne (The guy's a hero), this is an improvement over Living Economy which comes bundled with the full version of OOO. Choose not to install Living Economy when your are given the option on installation of OOO, and use this instead. Better in many ways.
I'll stop now before I start ranting about survival mods and weather mods.
Good luck, and enjoy.
Edit. Typos.