Answer: Without inspecting the plant, it's difficult to completely diagnose the problem. However, what you describe sounds suspiciously like overly saturated soils. The brown in the center of the leaf (where the leaf veins join) indicates the vascular system is stressed. When soils remain too wet the roots can suffocate and the vascular system can collapse. To avoid over-watering, make sure there are adequate drainage holes in the bottom of the ceramic pot and don't let water sit in the tray. Allow the top inch of soil to dry out before thoroughly watering your plant. If the whitish material on the top of the potting soil is crusty and hard, it is simply a collection of salts from your water. It won't hurt the plant or the soil but if you find it unattractive you can scrape it off the top of the soil. To avoid, use distilled or bottled water to water your plant. If the whitish material is soft and hairy, it's a fungal growth, brought about by overly wet conditions. If this is the case, correct the watering and drainage problems as outlined above and it should disappear.
Best wishes with your new plant!
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