April-Zen Recipe - Feedback Appreciated!

First brew of the season! A late-blooming Marzen... so, an April-zen!

This will be my crew's 3rd all-grain batch, and we've decided we want to try a double-decoction in order to gain access to the pantheon of the brewing gods. Figuring that the decoction will add some caramelly-ness, I've slightly lowered the amount of caramel malts; is that a good plan?

Also: any way to calculate a target OG/FG from this recipe? I'm adapting and changing some other recipes so I don't reaaally know what these numbers are.

7 lb Vienna malt
3.5 lb Munich malt
1/2 lb Crystal 20
1/3 lb Caramunich

1 oz. Hallertau - 60 min
1 oz. Hallertau - 30 min
0.5 oz Saaz - 2 min

Yeast starter - yes, but what size? (I have 3 days to make one)

Dough-in with 15 quarts of water at 130F, let sit for 20 minutes.
Decoct 1/3, bring to 150 for 30 mins; boil for 20 mins, re-add to MLT, let sit for 60 mins (target 152 F)
Decoct 1/3, boil for 20 mins, re-add to MLT for mash-out

60 minute boil

Primary at 50F; lager at 35-40 for 4-5 weeks.

I think the original recipe may have too much Vienna in it; Brewing Classic Styles recommends a 5:4:3 mix of Classic Pilsener, Munich, and Vienna. I think I like that approach, so I've adjusted the recipe below to use that instead. Thoughts?

5 lb American 2-row malt
4 lb Munich malt
3 lb Vienna malt
1/2 lb Crystal 20
1/3 lb Caramunich

1 oz. Hallertau - 60 min
1 oz. Hallertau - 30 min
0.5 oz Saaz - 2 min

Yeast starter - yes, but what size? (I have 3 days to make one)

Dough-in with 15 quarts of water at 130F, let sit for 20 minutes.
Decoct 1/3, bring to 150 for 30 mins; boil for 20 mins, re-add to MLT, let sit for 60 mins (target 152 F)
Decoct 1/3, boil for 20 mins, re-add to MLT for mash-out

60 minute boil

Primary at 50F; lager at 35-40 for 4-5 weeks.

Right, so, I think we've arrived at a final recipe/mash schedule here.

Starting in the morning, but always up for feedback!

Note: because I've only done AG a few times and this is the first decoction I've done, I'm putting in a lot of process notes that aren't strictly part of a "recipe." You can ignore them, or have a laugh at me for neuroses.

5 lb Pilsener
4 lb Munich malt
3 lb Vienna malt
1/2 lb Crystal 20
1/3 lb Caramunich

1 oz. Hallertau - 60 min
1 oz. Hallertau - 30 min
0.5 oz Saaz - 2 min

Yeast: WLP 838 Southern German Lager
Yeast Starter - 1 qt, gravity = 1.42, 1 day fermenting

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Mash Schedule:

Dough-in: 15 quarts of water (1.25 qt per lb) at 130F, to bring mash to 122F.
Protein rest (122F) for 50-60 minutes (aim for 50 or less if possible).

First decoction:At start of protein rest, decoct 1/3 of thick mash; bring to 150F for 10 minutes, then to boil for 20 minutes; stir often.

Infuse decoction back to MLT; target temp 152F. Saccharification rest for 90 minutes. Add up to 2 quarts boiling water to maintain temp.

Second decoction: At 2 hours (1 hour into sacch. rest), decoct 1/3 mixed thick/thin mash. Bring to boil, hold at boil for 20 mins, re-add to MLT for mash-out. Target temp 168 or higher.

Lautering: Vorlauf the first few quarts.
Sparge: 4.5 gallons at 170F. Take spec. grav readings until gravity of runoff = 1.008. (Use saucepan to cool 1/2-cup samples).
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Target volume to kettle: 6.33 gallons.

60 minute boil:
1 oz Hallertau at 60; 1 oz Hallertau at 30; 0.5 oz Saaz at 3
Irish Moss at 15

Primary at 50F; lager at 35-40 for 4-5 weeks.