Following your recent notice concerning the Sscience Eexhibition, I am writing, first and foremost, to express my gratitude for considering our opinions regarding the event. Following your recent notice concerning the science exhibition, I am writing, first and foremost, to express my gratitude for considering our opinions regarding the event.

Following your recent notice concerning the Science Exhibition, I am writing, first and foremost, to express my gratitude for considering our opinions regarding the event. Following your recent notice concerning the Science Exhibition, I am writing first and foremost to express my gratitude for considering our opinions regarding the event.

The commas can be optional.

In addition, I would like to inform you that in my view the tickets should be free, so that a huge number of people could attend, even if theyspecially those that could not normally afford it. In addition, I would like to inform you that in my view the tickets should be free, so that a huge number of people could attend, especially those that could not normally afford it.

In addition, I would like to inform you that in my view tickets should be free, so that a huge number ofmore people couldan attend, even if they could annot afford it. In addition, I would like to inform you that in my view tickets should be free, so that more people can attend, even if they cannot afford it.

"Huge" is too informal. This is describing a future event so "can" is better.

In addition, I would like to inform you that, in my viewopinion, tickets should be free, so that a hularge number of people couldan attend, even if they could annot afford it. In addition, I would like to inform you that, in my opinion, tickets should be free, so that a large number of people can attend, even if they cannot afford it.

As rRegarding the question of what activities can be performed, I must confess to being indecisive. Regarding the question of what activities can be performed, I must confess to being indecisive.

As regards to the question of what activities can be performedthere should be, I must confess to being indecisive. As regards to the question of what activities there should be, I must confess to being indecisive.

"Perform" would be more appropriate if the activities are performances.

As rRegarding the question of what activities can be performeddone, I must confess to being indecisive. Regarding the question of what activities can be done, I must confess to being indecisive.

We usually use the "do" verb when describing activities.

It would be a good idea if people could take part in workshops related to the topic,; however, It may increase the budget. It would be a good idea if people could take part in workshops related to the topic; however, It may increase the budget.

"However" is a conjunctive adverb and should not be used as a conjunction.

Despite that, I consider it an fantastic opportunity to get our community interested in some environmental issues and their possible approachesolutions. Despite that, I consider it a fantastic opportunity to get our community interested in some environmental issues and their possible solutions.

Despite that, I consider it an fantastic opportunity to get our community interested in some environmental issues and their possible approachesolutions. Despite that, I consider it a fantastic opportunity to get our community interested in environmental issues and their possible solutions.

"Some" isn't necessary here. Use "certain" or "particular" if you want to specify that this isn't referring to environmental issues in general, for formality.

Despite that, I consider it an fantastic opportunity to get our community interested in some environmental issues and theirpropose possible approaches. Despite that, I consider it a fantastic opportunity to get our community interested in some environmental issues and propose possible approaches.

Thank you very much again for your interest in feedback from the community. Thank you very much again for your interest in feedback from the community.

The original sentence sounds more like something that would be used if you were the event organizer responding to a letter.