As for the first group:
- 私はその人と話すと元気になる。Whenever I talk with that person, I feel uplifted.
- 私はその人と話して元気になる。I talk to that person and feel uplifted.
A. 私はその人と話す
B. 元気になる
In sentence 1, there is a causal relation between A and B, where A is the cause and B is the result/effect. In my rough and intuitive understanding, A has the function of a switch or a trigger for B.
In sentence 2, the relationship between A and B can not be expressed with a short phrase like sentence 1, but A is like a condition or means for B to be executed smoothly. In my rough and intuitive understanding, A has the function of helping B.
So my attempt is:
- 私はその人と話すと元気になる。
- Whenever/When I talk with that person, I feel uplifted.
- I talk with that person, so I feel uplifted.
- 私はその人と話して元気になる。
- I feel uplifted by talking with that person.
As for your attempt, sentence 1 is perfect and sentence 2 is somewhat correct.
Before talking about your attempt for sentence 2, the sentence 2 in Japanese is not a perfectly good example, because 私はその人と話す is not so appropriate as the means of 元気になる compared with like 一晩{ひとばん}眠{ねむ}る, 運動{うんどう}する or 薬{くすり}を飲{の}む. These are used as:
- 一晩眠って元気になる。
- 運動して元気になる。
- 薬を飲んで元気になる。
As for the second group:
- 私はその人と話すと喫茶店に行きます。Whenever I talk to that person, we go to a coffee shop.
- 私はその人と話して喫茶店に行きます。I talk to that person, and go to a coffee shop.
C: 私はその人と話す
D: 喫茶店に行きます
For sentence 3 and 4, you reported that sentence 3 is judged to be wrong in your textbook, but, I think, grammatically there is no problem in it. I also think sentence 4 is not so naturural, though it is grammatically correct. However, since the relationship between C and D is not so close, they are just unnatural.
If you want to describe the contents like sentence 3 or sentence 4 that I said grammatically correct, it is essential to divide C and D into two separate sentences, or to add some proper phrase that makes C and D more closely related.
An example of improving sentence 3:
- 私はその人と話をすると何故か喫茶店に行きたくなる。
Whenever I talk to that person, I feel like going to a coffee shop for some reason.
An example of improving sentence 4:
- 私はその人と話をして歩くことが体に良いと分かったので、私は歩いて喫茶店に行く。
I understand walking is good for the body by talking with that person, so I will walk to a coffee shop.