help needed asap....

 
Hi.

I am new to postgres and i need help from u.i hope i get positive response.. though my questions mite seem silly to u...

iam working on postgres.. i have around 1 lakh records in almost 12 tables..
1 ) when i try to query for count or for any thg it takes a long time to return the result. How to avoid this

2) also i want to know how to increase the  performance..( i do vacuum once in a day)

3) apart from that iam connecting to it through asp.net.. so when i try to fetch rcords the connection breaks..
how to avoid this..(very immp)

4) also in the tables  i put a column -- serial id . so when i try to insert new records after deleting the records(lets say at that time the last sequence number was 100).. when i insert new record it will start with 101..
suppose the sequence number reaches its maximum limit can i use the previous 1-100 values, by using the cycled option.

Thks..