Akun Viking Russia River Cruise Amount of Roubles used during trip?

We will be departing June 1st on a St Petersburg to Moscow cruise aboard Akun. We will have one more night (on own) in Moscow prior to heading home after the cruise, and wondered how many Roubles we might use. Does anyone have a suggestion of how many are needed for use during the trip for, food (bought during free time) bathroom access, museum entrance tickets, etc?

Also, did one use Roubles to tip quides?

Any other tips or information on this cruise would be wonderful. Thank you!

Welcome to Cruise Critic. I think you will reach more river cruisers if you post this on the River Cruising forum here. You might also research on the Ports of Call boards, find the one that covers Russia. EM

Thank you, I will do that.