Finishing my Wordpress website - making full responsive and fast

I have my website almost ready to advertise, but there are some problems I can't fix on my own. The website is [login to view URL] and It is a videographer team website. This site is using wordpress with the theme TheGem, and the Slider revolution plugin. Things I want to be made: - A "down narrow" on the first page/slider on positioned to the center of the screen, under the "Görgess lejjebb a szolgáltatásinkért, filmjeinkért" text. After clicking to the narrow, The website should be scrolled down to the next segment. - In the "Rólunk" segment, the left text-column should be animated when the viewer reaches It. It should making a sliding effect from left to Its final position. - In the 'Stábtagjaink' segment, I want to add more team members, as It highlights them. The problem is, if I add more than 4, It will display them in a new row, making the segment bigger. What I want to do is, show every team member in one line, but only 4 on the screen. So the viewer should click on left or right to scrolling to seeing everybody. (if I'm not understandable please tell me) Responsive things: - There's no video background on the phone version, but the background picture's (wich is the first frame of the video) center isn't the best for the phone version. The picture have to be moved a little to the right so camera's lens will be in the center. - In the Rólunk segment I want to display the text and the video as well full-screen width. I know there is that line on the left. I need It in the PC/tablet version, but not in the phone version, It doesn't look great here, and makes the site unreadable. - In the Filmjeink segment, there is a problem with the thumbnails' speed in phone version. Some are really quick, some are slow. All of them should be smooth. - The "Rólunk mondták" is a testimonials segment. There are 2 problems with this in the phone version: When 2 testimonials changing, there is a few seconds, when the segment is empty, and It makes itself smaller so It is like a blinking. This should be fixed. 2nd: The text should be as wide as possible because this is unreadable too. - Make the site as fast as possible while these visible effects remain. like the video-background.