Do people mind a lot if there are lots of same words throughout the novel like "He" or "I" or any other words, maybe even combinations such as "He said" "He looked" ? I don't, but I wonder do other people notice it and do certain words which repeat through the novel turn them off at some point, and maybe if someone feels generous he or she could give an advice on how to evade this.
Small words like the, he, it etc are invisible and readers don't notice repetitions of them. In addition, trying to avoid saying these can lead to horrifically awkward sentences that are way more noticable and awkward than the small word repetition ever would have been.
"Said" tends to be invisible and replacing it with much more noticeable words like "squawked" or "ejaculated" also leads to disturbingly awkward phrases and it's often better to just say "said". Bear in mind that not every line of dialogue needs a dialogue tag. A new paragraph indicates a new speaker. An action can indicate who's speaking (this goes in the same paragraph as the speaker) for example instead of:
"Hi," said Jane.
"Hi," said Jack.
"It's so annoying when the buses are late all the time," said Jane.
"Yeah, you wait for half an hour then three turn up at once," said Jack.
"And it's always worse when it's raining." said Jane
Could become:
"Hi, " said Jane.
"Hi." Jake smiled at her.
Jane looked at her watch and sighed. "It's so annoying when the buses are late all the time."
"Yeah, you wait for half an hour then three turn up at once."
"And it's always worse when it's raining." Jane laughed.
That's gone from 5 "said"s to just one, and not a single one replaced with a synonym. Not that all possible said synonyms are bad. They're fine when they're the most fitting word to use and too many actions to indicate who's speaking make the characters come across as twitchy (especially if you overuse stuff like shrugged, nodded or changes in facial expression as actions). None of these things are bad unless done excessively. And you can get away with a lot of "said"s without anyone noticing because it tends to be invisible.
Regarding "he looked" - overuse of any word that relates to senses or sensory organs may indicate that you are using too much filtering. For example:
Filtering: Jake looked at the sky and saw that it was grey.
Not filtering: The sky darkened.
If you've already established that Jake is the POV character, whenever you mention anything (like the colour of the sky) the reader will know it's your POV character that's observing it, so you don't need to say that they observed it. Sometimes, filtering used sparingly can be very excessive, but used excessively it creates a distance between the reader and the character and it can feel like you're reading a story about eyes doing this and ears dong that and eyes falling upon... etc etc etc. In any case, excessive use of all sense/sensory organ words are an indicator that filtering may be an issue.
The worst thing you can do is replace excessive filtering with synonyms to avoid repetition: "her gaze fell upon the sky and observed that it was grey. Her eyes glanced at the washing which she noticed was still on the line. Her skin felt the cold rain drops start to fall and she saw that the washing was starting to get wet" etc etc etc It's still filtering even if you eradicate all the repetition.