Higgins is a fairly deep lake with a max depth of 135 feet, but an average depth of around 40-45 feet. Bass, pike, and walleye are failry common in the lake as well as your usual pan fish. I have always had good luck with smaller rapalas, crank baits, and some top water baits for the early morning. For some deeper trolling all I have ever done is use a basic trolling rig with a spoon. (Daredelvil have always done well for me.) My trolling rig is got a weighted bottom that keeps the lure just a few inches off of the bottom. Of course you might need to adjust the depth you fish depending on where they are marking on your finder. Best of luck and have a good time on the lake.
The trout could be going well by the end of the month if it stays cool and you could do well with the downriggers. Spoons usually get it done for the better "eater" lake trout but if you want to go after the 15-30# fish cowbells are the best bet. There are some inland "steelhead" in there but they are few in number. Perch can be finicky in the super clear water but should be shallower (20-35') around the end of the month, if you get a cloudy day you can find them in the 15-20' water. There are about 500 rockbass per acre of water so if you've got kids you can keep them entertained forever.
If you want more details on any of the above PM me and I can give you some locations.