Reads multiple feeds. Output can be customized via templates. Is displayed via Shortcodes.
PHP 5.3 is available since June 2009. It introduced some long overdue features to the language and I refuse to support legacy junk. Please ask your hoster to update, kindly.
That depends on two aspects: Feed response time and feed size. Each feed you add increases the time needed to display the final page. The results are cached, so most of the time the page will render in a snap. If you'd like to see how long the page rendering takes when the cache is expired, have a look at the logfile (/wp-content/multi-feed-reader/reader.log). Look for the last line containing "template generated". It contains the durations.
Rule of thumb: On average, one feed requires one second. 5 Feeds are fine. 10 might work. 20 is probably too much. Your mileage may vary :)
That would be awesome!
Visit https://github.com/eteubert/multi-feed-reader, fork the project, add your feature and create a Pull Request. I'll be happy to review and add your changes.