RSS - feed display based on last reply date ?

I am running 4.1.17 and I can see RSS feed creation feature in IPB Admin Panel.

I tried to create a new RSS feed for the topics of my forum.

1) The problem is it displays the RSS feed sorted by Topic Posted Date, but I need it to display based on latest reply date.

2) Max number of RSS items possible is 100. But I need 150 items.

Can you please tell me where to edit and get these done ?

I am open to editing of source code files.

Thank You !