Hi Amit,
To answer your questions ,
1) No you don't need to Install Sybase separately , this activity will be performed by Installation tool (SWPM).
2) Series of steps are ,
- Download all required packages from marketplace .
- Extract SWPM in a directory and start sapinst
- Select the product you want to install
- Follow the guided procedure and provide location of Softwars, Installer will automatically install DB and ECC and will start ECC.
Once installation is completed you can login directly using SAPGUI.
Hope this is helpful.
Regards
Bhupesh Akkineni