Anniversary in Japan

I am planning with my wife to celebrate our anniversary in Japan for 2 last weeks of March.
Never been to Japan before, we have a 2 years old baby.
First of all, is Japan a babies friendly place.
Im planning to start from Osaka for 3 nights, than Kyoto 3 nights than to Tokyo. What do you think of this plan, do i need to add,cut, or squeeze a city into this plan.
which hotels are recommended based on a 5 stars selection, are hotels in Japan helps in making your event unforgettable like USA where you get chocolates and room upgrades for your occasion.
Traveling between cities, how easy is't with a baby and luggage. How about the metros in cities, are they easy to navigate as we don't speak any Japanese language.
Are American Express & Visa card widely accepted?

Appreciate your help.

Im planning to start from Osaka for 3 nights, than Kyoto 3 nights than to Tokyo. What do you think of this plan, do i need to add,cut, or squeeze a city into this plan.

How much time will you be spending in Tokyo? Where are you flying out of?

which hotels are recommended based on a 5 stars selection

They're pretty much all highly rated ;)
Kyoto in particular doesn't have a lot of selection. But lucky for you a Ritz Carlton just opened up there.

are hotels in Japan helps in making your event unforgettable like USA where you get chocolates and room upgrades for your occasion.

Some offer complimentary services like wine, chocolates, or flowers. I don't know about upgrades though. Perhaps they may give them to you if they are available, but know that late March is a busy time where a lot of hotels start to become fully booked.

Traveling between cities, how easy is't with a baby and luggage.

No problem as long as you don't have excessive amounts of luggage. Consider sending suitcases ahead, and using a sling carrier over a stroller.

How about the metros in cities, are they easy to navigate as we don't speak any Japanese language.

Yes, major public transport systems in Japan typically have bilingual signs.

Are American Express & Visa card widely accepted?

Yes, visa is pretty much ubiquitous wherever credit cards are accepted. Amex is also widely accepted, but a little less so than Visa.