Form 16 multiple employers, tax benefits options

Hi Sir, I have following brief queries 
1. Multiple Form 16: I have changed job twice in Year 2011-12. Thus I am expecting 3 Form 16 from different employers. In case i pay tax in May 2012, before filing ITR, will there be any late penalty. 
Certain investments (like Infrastructure bonds, PPF) are not accepted by employers due to late submission. How can i claim benefits during ITR filing (how to submit supporting evidence to IT office). 
I also missed to furnish Medical bills for 2 months to previous employer. Can i take benefits of these medical bills also during ITR filing. How to submit proof 

2. What are the tax saving options/investments other than following, 
a) 80C -> 100000 limit 
b) 80CCf -> 20000 infrastructure bond limit 
c) 80 D -> health insurance 

3. I have booked a flat, and so far not taken loan. Is there any way, i can be benefitted in income tax. (ie exemption for service tax paid on Property, etc) 

Thanks a lot