I've been working to create a Bard using the 4e rules but have had very little luck in finding any source info that I am 100% sure is accurate. Is there a specific source book that introduced the class to 4e? If not, any suggestions on how to adapt the 3.5 rules in order to make it work?
The 4th edition Bard was introduced in the Players Handbook 2.
This companion to the Player's Handbook® core rulebook introduces the primal power source, which draws on the spirits that preserve and sustain the world. Player's Handbook 2 includes four classes tied to the primal power source: the barbarian, the druid, the shaman, and the warden. It also presents four new arcane and divine classes: the avenger, the bard, the invoker, and the sorcerer.
Heroes of the Feywild introduced the Skald options for the Bard class.
New subclasses include berserker barbarians, bardic skalds, druidic protectors, and wizardly witches. A slew of new powers, class abilities, and options accompany these new subclasses. There are rules for character themes, paragon paths, feats, gear, magic items, and the like. I'm particularly impressed by the gorgeous art in these sections, which ties in nicely to new story elements.
Arcane Power adds some more options
This book provides new archetypal builds for the wizard, warlock, sorcerer, bard, and swordmage classes, including new character powers, feats, paragon paths, and epic destinies.
If not, any suggestions on how to adapt the 3.5 rules in order to make it work?
3.x edition rules do not port cleanly to 4th edition. They are very different rulesets. If you were to homebrew a bard, the simplest approach is generally to look at what you want to do with it, take a class with similar (in purely mechanical terms) abilities and rewrite the flavour text for them.