I'm more familiar with pen and paper than with Kingmaker, so if anything I say is not accurate people can correct me, but I can still give some general pointers.

First of all, two-weapon fighting is typically much better with dexterity than with strength. This is primarily because the two-weapon fighting feats require dexterity as a prerequisite, and there are few options to get around it. If you do want to go the strength route, you're pretty much locked into Ranger as it's the only way to qualify for the necessary feats without crippling dexterity investment (which you really can't afford, especially as a dwarf), and you would rather be a Fighter to benefit from weapon training.

It's preferable to use the same weapon type in both hands, as feats that specialize you in specific weapons then apply to both of them. You want your weapon of choice to have favorable critical hit properties and to count as a light weapon. None of the weapons you've listed meet that criteria. Maces have poor critical hit properties, the estoc only counts as a light weapon in your main hand (not your off-hand), while longsword, scimitar, and falcata aren't light weapons. In general the kukri is seen as the best weapon choice for two-weapon fighting since it's a light weapon with great critical hit properties. You can use the effortless dual wielding Advanced Weapon Training option (if you have the DLC) to get around the requirement of light weapons, but at the same time you can use the focused weapon Advanced Weapon Training option to upgrade the damage of your kukris to hit even harder than those bigger weapons. As a result, effortless duel wielding is strictly outclassed.

Focusing in critical hits is important because two-weapon fighting lets you crit fish. The large number of attack rolls means you can score critical hits more consistently, and at higher levels you can get feats that cause debilitating penalties to enemies when you crit them. This has obviously powerful synergy with two-weapon fighting. It also makes the Fighter a very attractive class, as you need a lot of feats to get these benefits, plus it gives you access to weapon training and advanced weapon training which are superb.

Dipping Alchemist can be very solid. Mutagen and Extracts are great, and the Vivisectionist archetype is available to trade off bombs (which are not very useful if you're just dipping). Unfortunately it does slow down progression in your main class and has slower attack progression so your accuracy will suffer, but it can definitely be worthwhile.

As for stat points, the biggest and most important one is to try to pump your main attacking stat, be it strength or dexterity. Starting with a 16 is your absolute minimum, and you really want an 18 if possible (which is hard to do as a dwarf since you don't get a racial bonus to either strength or dexterity). Every extra point you can get matters, as it helps with accuracy and hitting stuff is super important.

One thing to keep in mind when creating a front-liner in Kingmaker is that AC is absolutely critical. Enemies in this game are extremely accurate and deal enormous amounts of damage, and can eliminate even very high HP front-liners in short order. This makes anything that boosts AC significantly more valuable.