I love this modpack so far, and I would like to give you some interesting tips from my own experience:
TechReborn Windmills can be a very good power source: each one is really cheap (a generator and a bit of Iron and you get TWO), and produces a decent amount of power without needing any real free space around it: 20 of those placed high up in the sky and connected to a Powercell with basic universal cables give you quite an amazing bit of power; speaking of Powercells, they are essentially cheap Tesseracts which work for energy only.
Longswords from Tinkers are great as always, but they are even better in 1.10: a Bone guard, Manyullyn rod, Steel head setup can oneshot basically everything with a bit of quartz slapped on, and give that awesome mobility the Longsword always gave.
If you can get your hands on a Spruce Sapling, a Firewood plate, Stone head, Copper binding, w/e rod Lumber Axe with Fortune 3 and a handful of Furnace Generators will solve your power problems for a long time and give your Botania Mana production an head-start.
But, most importantly, Knightslime is 1000% worth it: it is downright the best tool rod, with an insane speed boost and a great durability (optimal for a ridiculously fast Hammer, with plates made out of Cobalt and Ardite, and the head made out of an easy-to-get material like Stone or even better Copper).
With all the Copper in your tools (and a wise usage of the Experience Obelisk), you will have accumulated a lot of experience: what is the best use for this? My own best bet would be to create an Emeradic AIOT and pump it up with Efficiency and most importantly Mending (which are ez pz with a EIO inscriber): this will give you a very fast tool which is effective on everything and pairs up nicely with the Longsword to compress tools down to just two slots in your hotbar. Also, Emeradic Armour with protection 4 is amazing, you basically take no damage at all with a full suit and a Diamond Helmet with Probe. Spawner Changers are very useful, and can be used to get just as many wither skulls as you desire by plopping a spawner in the nether and changing it to a skeleton spawner, and slaying the big black skellies (no racism here) by using a Mechanical User with a good Cleaver (or even your Longsword, which could be undestructible and beheading 5 by the time you get to build a wither skellie grinder, and you can build a new sword from scratch anyways) in it; you can then go ahead and create a wither farm and end your power problems forever with the almighty nether star generator, which has no drawbacks unlike the xu one.
YMMV