I am not a fan of using SQL*PLUS as an interface to Oracle. I usually use yasql, but it hasn't been updated since 2005 and can do with some improvements. A quick Google search shows yasql and SQLPal. I am using linux, so SQLPal is not an option.
Are there any alternatives out there, or am I stuck with an interface that I do not like or one that is no longer maintained?
I presume that you want a low-overhead method of knocking out queries, but want more functions than SQL*Plus provides? Why not use Oracle's SQL Developer? It's free.
Install, make a new connection to your database, then just start typing a script. Press F5 to run it (or just the part of the script that you've highlighted).