Hello Amit,
1. On the shopping cart page currently the product image displayed is the Thumbnail image. How can I change it to show base image?
Ans: you can change this product image into base - catalog ->manage product -->image.
2. I have also added some custom fileds for the products. In the shopping cart it also shows the labels for these custom fields. How can i disable this option?
Ans: For this we need to code for this. If need contact me
3. I have added few Virtual products where no shpping is required. But for these products when order is placed it comes directly in the Completed state. How can I change to Pending state on placing the order.
Ans: need to check the order status in back end.