Shopping, expenses in Indonesia?

I am about 5 feet 11 inch in height, would I have trouble shopping for pants, trousers, full length jeans etc. And will they be expensive?

Also shopping for shoes (Formal sandals and closed dress shoes etc)and socks, my shoe size is 13 USA/12.5 UK/47.5 EUR and 2E wide. Will shopping for them  be difficult and also will they be expensive?

The scholarship that I will be on will cover accommodation (board & lodging); health insurance. Excluding this, will Rp 1500000 per month be enough

One and a half million per month will buy very little.
You'll be able to live on simple food but no beer and nothing expensive or you'll be starving after the fist couple of days every month.
You won't be able to afford the shoes you have pretty much zero chance of finding in that size anyway.
I'm a UK wide 10 and I've managed to find one pair of formal shoes in almost 4 years.