You have a lot of choices.
The first is whether to focus on Indian warfare, or on Indians as auxiliaries in battles between white armies. I think the bigger battles of the AWI and 1812 are best modeled in 15mm scale. In order to play out a battle with 5,000 or 10,000 men in each army on a ping-pong table with 25mm figs, units have to be shrunk down to only a few figures, so that their footprints fit on the map and the map fits the table.
Since you have decided on 28mm figures, IMO that scale best fits smaller battles and skirmishes, where one or both sides can reasonably be all-Indian. There were plenty of smaller battles in the big wars and between them, so you can build whatever white civilians and troops you like.
I recommend mounting individual figures on 1" X 1" square bases. That way you can use your figs for a great many different rule sets that model frontier warfare in a variety of ways.
Nearly all current skirmish and semi-skirmish rules call for individually mounted figures. Some rules suggest smaller bases, some call for round bases, but it seems that you always need to distinguish front from back of the base, which is easier with squares, and the squares fit better into close formations. Stands smaller than 1" seem to be sized for the older 25mm figures. Newer 28mm figs need a full inch. Small variations in stand size make little difference to play, IMO.
I use magnetic steel bases from Wargames Accessories, they're good quality, readily available and not too expensive. I make magnetized storage boxes for my armies.
Some rules, like the old "Firelock and Scalplock" set, are just 3 or 4 pages, designed to let players chase one another around the woods or the farmstead with a couple of dozen figures and a fist full of D6 for a happy afternoon of pot-shooting. Others, like Chris Peers' "A Good Day to Die", run to multiple volumes and try seriously to model unique cultural dimensions of Indian warfare via tactical and campaign rules. You should try out several sets and discover what approach best suits you and your friends.
Other posters have provided links to several good threads and rule sets. I'm going to link you to the "Moccasins" Yahoo group.
link
I know Yahoo groups are passe, but I never quite caught onto whatever was supposed to replace them – was it Facebook? Or smartphones? Something…
"Moccasins" is dedicated to wargaming Eastern Woodland Indian Warfare. The group's namesake rule set, "Our Moccasins Trickled Blood", is meant to support playing the largest frontier battles, like Fallen Timbers or Point Pleasant, as multi-player convention games. These scenarios were developed with Old Glory 25mm F&IW, AWI and Wayne's Legion in mind, still excellent figures at a good price, if you don't mind buying 30-figure bags.
While the group is pretty quiet these days, the old threads contain lots of useful information for the enthusiast and the Files section houses a ton of good material, including several rule sets, free for the downloading, that address frontier warfare from various perspectives. If you join and post, probably someone will answer.
Of course you want to read the history, not just wargame rules. Alan Eckert's historical novels are a great place to start. The People novels, that I've recommended before, include a volume or two on the Ohio country in pre-history. People of the Masks is set in the Hopewell culture.
Finally. You lucky dog. You live today in the middle of the Ohio country, the very heart of the old Eastern Woodlands. Kentucky is just across the river. You have dozens of important historical sites related to this era or to earlier history within an easy day's drive: Fort Ancient, Serpent Mound, Chillicothe Mounds, Daybreak Village, Marietta, Fort Pickawillany, Fort Ligonier, Fallen Timbers, Fort Miamis, Fort Meigs, Boonesboro, Blue Licks…to name a few.
When spring comes, pack up your girlfriend or a gaming buddy and take some day trips. There's nothing like walking the site yourself to see why they put the village just *here*, why the ambush was sprung *there*, just what the heat and humidity and mosquitoes were like on a summer afternoon 250 years ago. And sometimes the ghosts speak.