Mr. Naveed
First of all congratulations on purchase of your new ride. I also have Cultus 2010 (crystal tail lights)
1. I will recommend you to go for Fabric poshish/seat covers as it will get less hot in summer. (I am from Multan so you can assume how much heat is here during summer.)
2. Security systems are availeable from Rs. 1600 to Rs. 5000. But i will recommend you go for any security system withing 2000 to 3000 range. Steelmate is best but a bit expenssive. I myself is using a non branded security system which is going strong even after 7 years. Its brand was osaka and costed me Rs. 1800 for unit in 2010. P.S: Security system will cost you almost Rs. 4000 to 5000 including security alarm unit, 4 relays also known as motors, and labor.
3. Its your personal choice but 2-Din is not recommended neither navigation or touch screen in Cultus. Its simply waste of money coz Cultus head unit place is so low that you can not be comfortable driving and using navigation at the same time. I will recommend you a player which has its built-in USB option. You can get a branded one eg: Honda City 1-Din Audio player fresh condition in 4 to 4.5K. People change it to install Navigation or LCD unit in Honda City. You can go for a chinese one eg: RockMars or any other brand which only have FM and USB option as low as Rs. 1600. But if you dont wanna invest right now you can make changes to your existing unit with mp3 Module. i guess module will cost you Rs. 200 and tape wala will charge you for its labor at least Rs. 300. Else you can get a ready made branded head unit (1Din or 2Din) which is converted to USB from the auto market. it will cost you almost Rs.1000 depending on the player you are buying.
Chinese Head Unit , with Card, USB, FM option. range from Rs. 1600 to 3000
MP3 Audio Module will cost you in total approx Rs. 600 in your existing unit
A branded Honda City Audio Player in Fresh condition will cost you almost Rs. 4500
you can get all these things (seat covers/poshish, security system, audio player) from Model Town Link Road, Model Town C Block Market, Montgomery Road in Lahore.