Hello, thank you for giving the game a try! To address your questions:
1) I would suggest not picking Mining, you can learn Mining in the Goblin Village from an NPC just outside the Mine entrance in the Foundry.
At the moment, there is only one way to permanently increase attributes, and that is to max out a Skill which will give you a title and a +1 to a specific attribute.
There are also Potions that give you a temporary boost of +2 to a stat, they can be useful if you are about to engage in a fight or do some skill check which you have doubts about passing.
You can get a significant selection of Skills during the game-play though. Athletics can be earned by completing the quest to find 10 Honey for a Goblin Guard in the Tower. Most other skills are sold by an NPC in the Brothel on the second floor on SATURDAYS, but they cost a significant amount of money.
2) Battle exp depends on what enemy you defeat, Rats ad Hornets give 1-5, Wolves give 5-10 and Werewolves give 10-15 I believe.
3) Traps can be disabled withe a Spec in Guile, but you also need a Detection Spec in Perception to see them. The Damage range is 1-40 or 1-60 if you picked the "Bad Luck" Flaw.
4) The success is determined mostly by your Lock picking Lvl. In most cases the difficulty number is 15-20 (15 for chests and 20 for houses) and you roll a 1d20 for it, add +3 per Lockpick level and +1 per Agility and Luck score.
5) How far are you in her quest line? She offers sex as a reward when you bring her the Red Dress for a Quest, and after that you can start sleeping with her at night.
If you haven't started the quest line, you need to bring Goblin Reputation to ~30 for her to start giving you quests.
6) Magic does even less to Slimes. Any Bladed weapon essentially gives a +30% damage modifier against unarmored, fleshy targets. I think your main issue might be the fact that your Str is only 2, you can still increase your damage output by taking Acrobatics Spec.
But to answer your question, there are no better weapons at the moment. Have you taken the Arms Spec in Athletics? That should grant you the Multi Slash skill that does quite heavy damage with a Sword, the down side is that you might not be able to use it every turn.
7) Thank you, glad you like it!