First, I'd add another 2 lbs of Munich extract. Boost your gravity into the appropriate range for the style, add some more malty goodness.
Second, I'd eliminate the Cascades, and stick with the Hallertauer. Without knowing the AA% of your hops, it's hard to say how much exactly to use, but if I ballpark 4% AA, .75-1oz @ 60 min is probably about right for bittering. Use .25-.5oz of the Hallertauer @ 15 min for finishing, as well.
If you want something Märzen-like, don't use Windsor Ale yeast. If you're set on using an ale yeast, use something like Safale US-05, or Wyeast 1007 German Ale that will ferment very clean at the low end of it's temperature range (upper 50s, low 60s). If you're going to try lagering in your mini fridge, then don't use an ale yeast! Try using something German, such as Wyeast 2308 Munich Lager, 2633 Oktoberfest Lager Blend, or for dry yeast, maybe a Saflager-23.
I hope this helps you get started, but I'm sure that there are other members of HBT that have more experience than I do brewing Märzen-style lagers! Cheers and good luck.