1. When buying from an online retailer, how much do you take into consideration their waranty policy?
I always consider a retailer's warranty, be it online or otherwise. It can be a deal breaker if the retailer's policies are too harsh against its consumers.
2. How long do you think a warranty should be for products like cables, as well as electronics like switchers, splitters and converters (please be as specific as possible)?
For cables its fairly irrelevant since they either work or dont, I've yet to have a cable fail after some use, of course a 'limited lifetime warranty' is always appreciated since it ensures peace of mind.
For electronics I think a limited lifetime warranty should be provided, it's both feasible and easily protected against abuse, and it usually ensures customer loyalty as well.
3. In your opinion, what should happen if a product is returned to the manufacturer under warranty and found to have no defects? For example, should the end user be charges a restocking fee?
Since the user typically has already paid for transport to rma the item, it should be sent back free of charge, with proper diagnostic information such a situation should just about never happen.