Fees for bitcoind sendmany, limits for number of end addresses I have two questions, both about sendmany.

First, is there any limit on how much transactions can I send with sendmany? (Apart from bash's limit with maximal parameter length.) Is sending about 500 transactions OK?

Second, what will be the fees used when I send a lot of transactions (and thus, probably creating a big transaction)?
You can calculate your transaction size before sending the transaction. Here's some more info on that:

How to calculate transaction size before sending

A single transaction isn't limited to how many outputs it has, rather, there are some limits to how big a block is. You can read more here:

How many different destinations can a single transaction have?

EDIT:
After calculating the size, you can further calculate fees by using this method (it takes into account some code in main.h): 

What is the exact formula for calculating transaction fees?