Cleaning my 2.5 gal tank - with Platy fry

Question
We were very lucky - we set up our 2.5 gal tank with 2 Platy expecting to lose them as the tank cycled.  We've had them about 2 months and just lost the male last week.   We've been doing a "total tank teardown" because I didn't know we were suppose to do partial cleanings.  
I have a female platy who appears to still be giving birth (5 so far).  I haven't cleaned my tank for over a week (I actually thought she was dead at one point, never knowing she was pregnant) and it is NASTY.  It even has black cloudy spots on the walls that look like mildew.  

1)  Should I do another "tear-down" since it's so bad, or will partial cleanings eventually clear it up?  

2)  Should I wait until I think the female is finished having fry before i do anything?

3)  When I do a partial water change, how do I get the water out?  Just scoop it and try not to get the fish?  

I don't have any way of testing the water short of taking a sample to PetCo.

I SO appreciate your help.  I've already read a lot about taking the female out in a  few days and putting her in bigger tank until the fry are big enough to join her, separating male from female, etc.  I'm just hung up on the tank-cleaning issue.

Thank you SO much!
Tonya

Answer
Hello Tonya:  I use a very small gravel vacuum to remove water from smaller tanks.  They are usually under $10 at the local fish store.  I would not take out all of the water just about 10-20 percent.  I would never change all of the water unless you had something toxic in the tank.  I would also wipe down the glass walls of the tank on a regular basis.  Use a dedicated fish tank cleaning pad that does not have nor has ever had soap on it.  I would also invest in a mystery snail to help you keep up with the maintenance of the tank.  They do a good job but you will still need to do your part... dave