Can i rent a phone when i arrive in japan?

Hello, i am going to japan this april to see the beautiful sakura! first time going to japan so i took the chance to make full research on what i should do , where to go, etc... but i still am troubled with this one question: i know that my phone which uses GSM won't be usable in japan and i need to rent one. So i was wondering if i can rent one upon arrival and if yes where should i go to to rent it? any companies or specific places for foreigners doing tourism for a week or so that can go to to rent one?

also one more question if it's not too bothersome: i bought shinkansen tickets but i believe they're not usable for the usual subway stations right? do i have to still get a SUICA card or not?

Thank you

Better to book ahead for pickup at the airport or sent to your first hotel. Search through this forum, I have seen a few rental company recommendations.

yes you can rent a phone at most international airport.
there are shops that rent out phones at airport such as

http://www.softbank-rental.jp/e/rental-plan.php

https://www.jalabc.com/english/index3.html

while these are few (mentioned in forum) that you can book online and have it deliver to your hotel

http://www.globaladvancedcomm.com/

http://www.pupuru.com/en/

https://www.rentafonejapan.com/

As for your shinkansen it only cover you from point A to B, local train may or may not included depends on your purchased ticket.

either you get a day pass or individual ticket for local train.
electronic card like suica or passmo is for convenience of not having to carry small change or buying ticket at machine.
necessary or not depends on your preference and usage.

Regarding Shinkansen (bullet train) and local trains:
If you bought a specific Shinkansen ticket, that is good for that specific trip only. If you bought a JR Pass, it is good on all JR trains which includes Shinkansen and a lot of local trains within Tokyo. For other cities (Kyoto, Osaka, etc.) there are very few local JR trains running, so you will probably need to buy individual tickets, or an IC Card (like Suica and Pasmo etc.), or local passes.