This is fantastic, great work.
Here's a couple of notes to help you along :)
./bashrc has some logic for a separate aliases include which used to need to be manually uncommented but is defaulted to enabled now so you could change that line to
echo "alias eosc='eosc -H testnet1.eos.io -p 80'" >> ~/.bash_aliasesso that it doesn't pollute a potentially existing ./bash_profile.
Notice i've also removed the ./ since after you run cd /eos/build && sudo make install the eosc binary is put into the PATH. ( "add the path to the eos binaries to your $PATH variable" also shouldn't be necessary anymore )
The data-dir is subject to change based on whether you're running a local node or not. Your best bet would be to do sudo find / -name data-dir and grab the location from there, for instance mine is at:
/home/eos-test-box/eos/build/programs/eosd/data-dir
Thank you for your advice, @nsjames! I've edited the post to include your suggestions and thank for your feedback.