NETGEAR ReadyNAS memory exhaust

Hello, thank you for your advices..

I just have seen this tutorial earlier (link below), saying that i could upgrade default 2GB of ram inside ReadyNAS to 4GBs. I thought it will be better, so i bought the memory module at ebay as brand new for cheap price. I plan adding only USB TV TUNER in a future along with DVBlink server for R6. Because I thought, that handling dual DVB TUNER and channels and streaming it inside my home network (to certain PCs), will be cpu and mem consuming.. maybe not.
http://ptarmiganlabs.wordpress.com/2013/08/16/add-more-ram-memory-to-readynas-rn312/

I have made 2 screenshots meanwhile, here they are:
1st: top command
https://www.dropbox.com/s/zuq5yrdk6nhrle6/Screenshot%202014-09-02%2018.56.26.png?dl=0
2nd: htop command, proccesses sorted by mem in %
https://www.dropbox.com/s/vcevi79kzyccf8g/Screenshot%202014-09-02%2018.58.05.png?dl=0

Forum didnt accepted images directly, you have to copy and paste urls into your browser. Sorry for inconvnience..

linux command "free" outputs this:

root@NAS:~# free
             total       used       free     shared    buffers     cached
Mem:       4035472    3988500      46972          0         72    3764676
-/+ buffers/cache:     223752    3811720
Swap:       523708          0     523708

If memory is consumed by pre(caching) standartly, this data above and also below, should be ok. Can you confirm? I dont know if this is normal linux and ReadyNAS 312 behaviour. If it is.. i just worry too much :-D

linux command "cat" outputs this:

root@NAS:~#  cat /proc/meminfo
MemTotal:        4035472 kB
MemFree:           47896 kB
Buffers:              72 kB
Cached:          3762440 kB
SwapCached:            0 kB
Active:          2002972 kB
Inactive:        1923676 kB
Active(anon):     105188 kB
Inactive(anon):    65456 kB
Active(file):    1897784 kB
Inactive(file):  1858220 kB
Unevictable:           0 kB
Mlocked:               0 kB
SwapTotal:        523708 kB
SwapFree:         523708 kB
Dirty:             14588 kB
Writeback:             0 kB
AnonPages:        164404 kB
Mapped:            33720 kB
Shmem:              6240 kB
Slab:              34540 kB
SReclaimable:      21716 kB
SUnreclaim:        12824 kB
KernelStack:        1624 kB
PageTables:        10064 kB
NFS_Unstable:          0 kB
Bounce:                0 kB
WritebackTmp:          0 kB
CommitLimit:     2541444 kB
Committed_AS:     850148 kB
VmallocTotal:   34359738367 kB
VmallocUsed:        2784 kB
VmallocChunk:   34359726324 kB
DirectMap4k:        3008 kB
DirectMap2M:     4182016 kB

Htop and top output same data but Htop is more detailed and with various data sorting options. (It comes from the "available applications" in webadmin of my ReadyNAS 312)

Yes, i come from windows OS. I dont know linux very much, so i expect windows behaviour, sometimes maybe where i should'nt. I know only basic linux commands and those commands useful for my ReadyNAS (like for installing TeamSpeak server, editing cron..). Thanks for your help i appreciate it.