Insignia the TV company has jumped on the band wagon with mobile electronics now and is selling them thru Worst Buy.
Will it sound allright? Don't know about the brand, as far as the equipment, I'm sure it will sound ok within itself.
But generally when using a line level adapter to innograte the rear speakers to RCA's, it sounds OK. If you want great, buy another headunit with RCA preouts.
It'll bump. Unless you're a big audiophile, you probably won't notice enough of a quality difference to make a difference. The biggest issue where the HU comes in is on the mid and upper range quality.