How much server power do I need?

I’m running a WP site which comprises a blog with a small video and photo gallery: http://www.esinem.com (NSFW!)

Recently, my SQL server has gone down a couple of times and also the whole VPS. Unfortunately, I’m piggy in the middle as the hosting techies are variously saying that it is some problem with a plugin or lack of resources. Unfortunately, I can’t judge if this lot with Apache and Ngix is up to the job to run a WP site with about 500 visitors each looking at about 3 pages for 2m 40s. However, I do know the easy answer if you provide systems is “Throw more resources at it (i.e. Gimme me your £!)” 😉 I’d value knowledgeable opinion.

OS Template: Red Hat Enterprise Linux 6 (64-bit)
Disk Space: 330 GB
Memory: 5120 MB
CPU Cores: 6 CPU(s)

Tech support said these are new queries which appearing in slow-query log for the most number of times. I’m guessing it might be something to do with the Striking theme but I haven’t had a definitive answer on that. Can anyone tell me in plain English what needs to be done to fix this?

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Count: 15352 Time=0.01s (82s) Lock=0.00s (25s) Rows=3660.9 (56202377), esinem_U6149613[esinem_U6149613]@localhost
SELECT option_name, option_value FROM wp_options WHERE autoload = ‘yes’

Count: 12515 Time=0.00s (1s) Lock=0.00s (0s) Rows=1.0 (12515), esinem_U6149613[esinem_U6149613]@localhost
SELECT COUNT(*) AS exist
FROM information_schema.tables
WHERE table_schema = ‘esinem_U6149613’
AND table_name = ‘wp_revslider_css’

Count: 1638 Time=0.00s (0s) Lock=0.00s (0s) Rows=0.0 (0), root[root]@localhost
SELECT user FROM mysql.user WHERE user LIKE ‘cpses_%’

Count: 206 Time=0.02s (3s) Lock=0.00s (0s) Rows=8905.1 (1834444), esinem_U6149613[esinem_U6149613]@localhost
SELECT post_id, meta_key, meta_value FROM wp_postmeta WHERE post_id IN (6813,6491,6842,6828,6804,6797,6785,6780,6771,6754,6751,6746,6741,6737,6701,6353,6691,6676,6671,6656,6650,6641,6585,6578,6570,6567,6562,6558,6541,6513,6498,6480,6469,6458,6451,6443,6438,6431,6414,6395,6364,6359,6348,6341,6338,6328,6316,6313,6307,6299,6292,6264,6246,6227,6220,6212,6207,6203,6187,6179,6172,6168,6161,6149,6131,6123,6102,6097,6093,6073,6045,6040,6033,6016,6006,5994,5989,5985,5970,5959,5951,5882,5734,5867,5849,5841,5819,5814,5798,5773,5767,5762,5755,5741,5685,5662,5651,5641,5615,5588,5318,5575,5548,5546,5539,5530,5470,5416,5386,5381,5321,5125,5250,5240,5189,5209,5200,5192,5184,5172,5168,5153,5127,5086,5088,5078,5062,4695,4922,4910,4899,4886,4881,4871,4853,4842,4830,4812,4793,4781,4778,4774,4753,4696,4714,4676,4629,4566,4558,4547,4532,4513,4494,4488,4478,4464,4424,4415,4389,4390,4381,4361,4299,4327,4337,4239,4126,4221,4197,4192,4183,4171,4153,4112,4076,4098,4089,4073,4056,4051,4043,4027,4017,4013,3996,3989,3973,3960,3950,3931,3918,3906,3895,3880,3844,3837,3381,3810,3796,3788,3780,3775,3770,3759,3746,3730,3728,3721,3706,3701,3698,3690,3653,3646,3633,3625,3603,3593,3562,3543,3415,3521,3475,3460,3449,3219,3384,3133,3356,3353,3330,3324,3310,3288,3262,3235,3231,3177,3158,3150,3119,3106,3073,3064,3020,3017,3001,2982,2975,2956,2949,2944,2923,2833,2901,2878,2885,2875,2868,2847,2842,2836,2825,2811,2795,2791,2786,2777,2772,2746,2716,2701,2689,2675,2658,2567,2595,2577,2560,2547,2485,2532,2521,2500,2475,2470,2468,2450,2445,2412,2399,2346,2385,2364,2357,2339,2333,2320,2311,2285,2260,2253,2233,2220,2212,2195,2118,2102,2084,2068,2049,2023,2013,2007,1991,1988,1970,1949,1934,1930,1921,1738,1859,1876,1855,1841,1835,1641,1783,1735,1717,1623,1615,1603,1596,1590,4674,1568,1544,1537,1514,1491,1485,1475,1454,1439,1406,1380,1251,1198,1196,1173,1140,1125,1122,1110,1048,1045,1039,976,955,948,922,856,846,836,785,783,777,767,764,754,654,644,640,1137)

Count: 155 Time=0.00s (0s) Lock=0.00s (0s) Rows=29.4 (4556), esinem_U6149613[esinem_U6149613]@localhost
SELECT remote_path FROM wp_w3tc_cdn_queue