Amazon EC2 Windows Ubuntu

I am new to AWS EC2 so that I make this post for some questions.

1) Right now, I am considering running some script on the server. I use two tools usually. One is a software can only be used in Windows. The other is just python. Should I open two instances, one for windows, one for ubuntu? Or just one instance of Windows with Git Bash installed? I want to be cost and performance efficiently.

2) I am not going to use the script very often (usually 2-3 hours per day or 10-12 hours per week). Therefore, is it easy to schedule those jobs automatically across the instances? I mean it can automatically turn off and restart given appropriate time.

3) Some of the script involves web scraping. I am also wondering if it is ok to switch IP address every time I run the script. Mainly, it is for python script.

Thanks.