Dear Anil,
For Purchase Transaction Type 100
For Sale Transaction Type 200
TS01or FTR_CREATE - Create Contract
TS02 or FTR _EDIT - Change Contract
TS04 or FTR_EDIT - Contract Settlement
TBB1 - Post to Accounting
Month end activities
Dividend Posting: FWSO/ FWZE
You may use FWBS: Manual Posting
Valuation: TPM1
2) Why we need different security class.
Say for example I have create security class for bonds
IF I do business transaction of all kinds of bond (Corporate or Govt Etc)you will not able to do reporting or Function(FWZZ) in it.
Hence its advise to create new class for each kind.
Hope this answer your question.
Regards,
Jain