Transaction fees actually have no exact rates. Technically you can even send some coins with zero fees if anyone is there to solve the transaction (mining).
Larger the transaction fee you allocate faster the miners pick your transaction as they would go for larger rewards.
There are many wallets that lets you define the fees.
This is not correct; I am not referring to bitcoin, I am referring to a comparison of all the major digital currencies. Some of them have well-defined transaction fees.
With blockchain technology the fee varies a lot. Sometimes I pay 70 cents to send btc (regular fee), other times it is more than a dollar. I guess we can't talk about the price but we could still define the fee by a few ways. The first option is to set the approximate fee for all the currencies and then right down that the fee is two times less than that of btc, for instance. Another option is that the fee is actually defined by the block size and stuff like that. There are even fee calculators. Thus we could perhaps write down the fee in percentage or something like that. Unfortunately, nowadays there is no such list.
Exactly, transaction fees can be described in many ways. A chart could have a list of different ways to look at fees for each currency, and the user could rank the criterion that was important to her. I imagine someone will post a Wiki for this and with the community updating it, it will have accurate results without too much work. It will be very important to consumers and businesses when deciding which crypto they are interested in.